feat: post composition redesign + budget allocation + brand identity (Rawaj)

Post Workflow:
- PostDetail full page (/posts/:id) replaces slide panel approach
- Post = 1 Caption Copy + 1 Body Copy + 1 Design + 0-1 Video
- copy_type field on Translations (caption/body)
- Composition endpoint returns rich data (content preview, languages, thumbnails)
- Stage auto-advances on translation/artefact changes (both link and unlink)
- "Translations" renamed to "Copy" in navigation
- GET /api/posts/:id, /api/translations/:id, /api/artefacts/:id routes added
- PostProduction: "New Post" creates → navigates to full page
- CampaignDetail: click post → navigates to full page
- Inline link picker (no modals) with search + rich item display
- PostComposition sub-components for caption, copy, designs, video, formats, readiness

Budget Allocation:
- Single source of truth: BudgetEntries (Campaign.budget deprecated)
- Budget mutex for race conditions
- Validation at all levels (main → campaign → track, expenses)
- CEO approval workflow: BudgetRequests table, public approval page
- Finance page: request budget UI, budget requests section
- Settings: CEO email field
- All emails branded with "Rawaj —" prefix

Brand Identity:
- Name: Rawaj (رواج) — trending/virality
- Deep teal palette (#0d9488), forest-tinted dark mode
- DM Sans font, custom SVG logo
- Consistent across login, sidebar, emails, public pages

Approval Workflow:
- Single reviewer per artefact (not multi-select)
- Reviewer redirect on public review page
- Server blocks submit-review without reviewer
- Review URLs use APP_URL (not server URL)

UI/UX:
- Scroll clipping fix: Modal, TabbedModal, SlidePanel restructured
  to avoid overflow-y-auto clipping native select dropdowns
- section-card overflow-hidden → overflow-clip
- All page titles via Header.jsx (removed duplicate h1s)
- CampaignDetail redesigned: prominent budget card, compact team

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client/src/index.css

@@ -504,7 +504,7 @@ textarea {
   background: white;
   border: 1px solid var(--color-border);
   border-radius: 1rem;
-  overflow: hidden;
+  overflow: clip;
   box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
   transition: box-shadow 0.3s ease;
 }