feat(pitch-admin): structured form editors, bilingual fields, version preview

Replaces raw JSON textarea in version editor with proper form UIs:

- Company: single-record form with side-by-side DE/EN tagline + mission
- Team: expandable card list with bilingual role/bio, expertise tags
- Financials: year-by-year table with numeric inputs
- Market: TAM/SAM/SOM row table
- Competitors: card list with strengths/weaknesses tag arrays
- Features: card list with DE/EN names + checkbox matrix
- Milestones: card list with DE/EN title/description + status dropdown
- Metrics: card list with DE/EN labels
- Funding: form + nested use_of_funds table
- Products: card list with DE/EN capabilities + feature tag arrays
- FM Scenarios: card list with color picker
- FM Assumptions: row table

Shared editor primitives (components/pitch-admin/editors/):
  BilingualField, FormField, ArrayField, RowTable, CardList

"Edit as JSON" toggle preserved as escape hatch on every tab.

Preview: admin clicks "Preview" on version editor → opens
/pitch-preview/[versionId] in new tab showing the full pitch deck
with that version's data. Admin-cookie gated (no investor auth).
Yellow "PREVIEW MODE" banner at top.

Also fixes the [object Object] inline table type cast in FM editor.

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

pitch-deck/middleware.ts

@@ -16,7 +16,7 @@ const PUBLIC_PATHS = [
 ]
 
 // Paths gated on the admin session cookie
-const ADMIN_GATED_PREFIXES = ['/pitch-admin', '/api/admin']
+const ADMIN_GATED_PREFIXES = ['/pitch-admin', '/api/admin', '/pitch-preview', '/api/preview-data']
 
 function isPublicPath(pathname: string): boolean {
   return PUBLIC_PATHS.some(p => pathname === p || pathname.startsWith(p + '/'))