fix: post images diversity — SUBJECT+SETTING+LIGHTING prompt

Та же проблема что и у обложек статей:
  старый промт 'Topic essence: первые 250 символов' был слишком абстрактным
  → модель рисовала свой дефолт (тёмный фон + геометрия)

Новый промт (3 некофликтующих параметра):
  VISUAL CONCEPT: конкретный предмет из getPostVisualConcept()
  SETTING: физический антураж (8 вариантов по seed из текста поста)
  LIGHTING + COLOR TEMPERATURE: конкретный свет

getPostVisualConcept(): 8 тематических категорий × 4-6 концептов
  AI, automation, cybersec, code, marketing, money, education, health
  + 12 универсальных концептов
Seed = hash первых 80 символов поста → детерминировано но уникально

src/services/postImages.js

@@ -75,15 +75,36 @@ async function generatePostImage({ post, channel, style = {} }) {
   // Извлекаем суть поста для промпта (первые 250 символов)
   const postExcerpt = post.replace(/[#*_`>]/g, '').slice(0, 250);
 
-  const prompt = `Editorial illustration for a social media post. Topic essence: "${postExcerpt}"
+  // Визуальная метафора — конкретный предмет/сцена на основе темы
+  const visualConcept = getPostVisualConcept(post, channel);
 
-Style: ${imageStyle.prompt}.
-${palette ? `Color palette: ${palette}.` : ''}
-Channel context: ${channel.niche || channel.name}.
-${style.image_prompt_instructions ? `\nChannel visual guidelines: ${style.image_prompt_instructions}` : ''}
+  // Антураж + свет — меняется по хешу поста (детерминированно, но разнообразно)
+  let seed = 0;
+  for (let i = 0; i < post.length && i < 100; i++) seed = (seed * 31 + post.charCodeAt(i)) >>> 0;
 
-Composition: 16:9 wide format, balanced, suitable for social media.
-Strictly: no text, no letters, no logos, no faces of real people.`;
+  const SCENES = [
+    { setting: 'warm oak desktop surface, afternoon sunlight from left window',    lighting: 'golden hour soft shadows', temp: 'warm amber' },
+    { setting: 'white marble surface, clean studio',                               lighting: 'flat professional studio', temp: 'cool whites' },
+    { setting: 'dark slate table, single focused overhead spotlight',              lighting: 'dramatic single point',   temp: 'high contrast' },
+    { setting: 'weathered wooden workbench, overcast daylight',                   lighting: 'soft even overcast',      temp: 'muted naturals' },
+    { setting: 'black velvet surface, rim lighting from behind',                  lighting: 'rim lit glowing edges',   temp: 'rich blacks gold' },
+    { setting: 'glass surface over city lights at night',                         lighting: 'city glow from below',    temp: 'multicolor bokeh' },
+    { setting: 'antique library floor, surrounded by books, candlelight',         lighting: 'warm candlelight side',   temp: 'amber parchment' },
+    { setting: 'frosted glass, winter morning, ice crystals at edges',            lighting: 'diffused winter morning', temp: 'icy blues whites' },
+  ];
+  const scene = SCENES[seed % SCENES.length];
+
+  const prompt = `Generate a 16:9 editorial illustration for a social media post.
+
+VISUAL CONCEPT: ${visualConcept}
+SETTING: ${scene.setting}
+LIGHTING: ${scene.lighting}
+COLOR TEMPERATURE: ${scene.temp}
+${style.image_custom_colors ? `BRAND PALETTE: ${style.image_custom_colors}` : (palette ? `PALETTE: ${palette}` : '')}
+STYLE: ${imageStyle.prompt}
+${style.image_prompt_instructions ? `CHANNEL STYLE: ${style.image_prompt_instructions}` : ''}
+
+RULES: no text, no letters, no logos, no real human faces.`;
 
   // Единственный провайдер: routerai /responses + gpt-5-image-mini
   // Цена: ~₽2.72/картинка. quality параметр не работает, всегда high.
@@ -142,3 +163,120 @@ Strictly: no text, no letters, no logos, no faces of real people.`;
 }
 
 module.exports = { generatePostImage, IMAGE_STYLES, IMAGE_PALETTES };
+
+/**
+ * Извлекает визуальный концепт из текста поста.
+ * Конкретные, материальные образы — не абстрактные.
+ */
+function getPostVisualConcept(post, channel) {
+  const t = post.toLowerCase();
+  const niche = (channel?.niche || '').toLowerCase();
+  const combined = t + ' ' + niche;
+
+  // Хеш для выбора внутри категории
+  let seed = 0;
+  for (let i = 0; i < post.length && i < 80; i++) seed = (seed * 31 + post.charCodeAt(i)) >>> 0;
+  function pick(arr) { return arr[seed % arr.length]; }
+
+  const patterns = [
+    {
+      kw: ['ии', ' ai ', 'нейро', 'llm', 'gpt', 'claude', 'chatgpt', 'искусственн', 'neural'],
+      concepts: [
+        'A vintage typewriter with keys pressing by invisible force, paper emerging with glowing text',
+        'An old brass compass spinning and settling on a new direction, surrounded by scattered maps',
+        'A seed germinating in dark soil, roots and shoots emerging simultaneously, close-up macro',
+        'A master key held up to warm light, intricate cuts visible, golden bokeh background',
+        'A book opening by itself, pages turning rapidly, text rearranging mid-air in warm library',
+        'An optical prism splitting white light into full spectrum, mounted on dark velvet surface',
+      ],
+    },
+    {
+      kw: ['автомат', 'бот', 'automat', 'workflow', 'n8n', 'zapier', 'make', 'скрипт'],
+      concepts: [
+        'Vintage clockwork mechanism — interlocking brass gears in motion, macro close-up, amber light',
+        'A domino chain in the moment of falling, each piece a different color, motion blur',
+        'Factory assembly line condensed to a tabletop, small objects moving through stages, long exposure',
+        'A rube goldberg sequence frozen mid-action, multiple contraptions in motion',
+        'Time-lapse of a city intersection at night, light trails forming perfect flow patterns',
+      ],
+    },
+    {
+      kw: ['взлом', 'хакер', 'безопасн', 'фишинг', 'вирус', 'cyber', 'hack', 'secur'],
+      concepts: [
+        'A vintage combination lock under dramatic side lighting, tumblers visible, dark background',
+        'A glass door with a hairline crack spreading, red emergency light leaking through fracture',
+        'An old steel safe door hanging slightly open, papers spilling out, harsh spotlight',
+        'A chain with one shattered link, chrome and steel, dramatic spotlight on break point',
+      ],
+    },
+    {
+      kw: ['код', 'разработ', 'програм', 'code', 'develop', 'software', 'api', 'github'],
+      concepts: [
+        'A craftsman workbench covered in precision tools, each perfectly placed, workshop window light',
+        'An architect drafting table with blueprints unrolled, compass and ruler in use, desk lamp',
+        'Knitting needles mid-row on a complex pattern, wool threads crossing precisely, natural light',
+        'A mason building a wall one brick at a time, each brick different texture, golden hour',
+      ],
+    },
+    {
+      kw: ['маркетинг', 'реклам', 'продвиж', 'seo', 'контент', 'growth', 'аудитор'],
+      concepts: [
+        'A megaphone lying on a table, vintage brass, city map spread underneath it',
+        'Seeds being planted in geometric rows, birds-eye view, garden tools aside, spring light',
+        'A lighthouse beam sweeping over foggy harbor, ships turning toward the light',
+        'A vendor market stall being set up attractively, colorful awning, morning light',
+      ],
+    },
+    {
+      kw: ['деньг', 'финанс', 'инвест', 'бизнес', 'прибыл', 'доход', 'money', 'business'],
+      concepts: [
+        'A vintage scale perfectly balanced with different objects on each side, warm studio light',
+        'Stack of different vintage coins photographed from above, macro, warm lighting',
+        'A piggy bank on a wooden surface with a single coin mid-air above it, soft focus',
+        'Growing seedlings in small pots arranged by height, morning light through window',
+      ],
+    },
+    {
+      kw: ['обучен', 'курс', 'урок', 'учеб', 'знан', 'навык', 'learn', 'educat'],
+      concepts: [
+        'Open textbook with handwritten notes in margins, pencil resting on page, desk lamp',
+        'Stack of colorful books with a cup of coffee, cozy reading corner, soft morning light',
+        'A graduation mortarboard on stack of books, warm sunlight from side',
+        'Hands writing in a notebook, pen visible, blurred background of bookshelf',
+      ],
+    },
+    {
+      kw: ['здоровь', 'спорт', 'фитнес', 'еда', 'питан', 'health', 'fit', 'food'],
+      concepts: [
+        'Fresh vegetables arranged artfully on white surface, overhead shot, natural light',
+        'Running shoes on wooden floor, morning light casting long shadows',
+        'A glass of water with ice and mint, condensation visible, clean white background',
+        'Yoga mat rolled out near window with morning light streaming in',
+      ],
+    },
+  ];
+
+  for (const { kw, concepts } of patterns) {
+    if (kw.some(k => combined.includes(k))) {
+      return pick(concepts);
+    }
+  }
+
+  // Универсальные — нейтральные но конкретные
+  const generic = [
+    'A single lighthouse on rocky coast at dusk, warm light in tower, dramatic sky',
+    'An empty stage with single spotlight on plain wooden chair, theatre atmosphere',
+    'A vintage compass on worn leather journal, mountain wilderness background',
+    'A door slightly ajar with warm light escaping, curious hallway perspective',
+    'A single match being struck in complete darkness, dramatic flare close-up',
+    'A crossroads sign in fog, gravel road, dawn light breaking through',
+    'A paper boat on still water, single ripple expanding outward, minimalist',
+    'An old film projector casting beam of light, dust particles visible, cinema',
+    'A telescope pointed skyward from rooftop, city lights below, stars above',
+    'A bridge disappearing into morning fog, pedestrian perspective',
+    'A ceramic coffee cup with steam rising, morning light through window',
+    'An open notebook with a pen and fern plant, flat lay, natural light',
+  ];
+
+  return pick(generic);
+}