feat(pitch-deck): data room — file sharing and investor uploads

- lib/dataroom-storage.ts: local volume storage (DATAROOM_PATH env var,
  default /data/dataroom) replacing NextCloud WebDAV
- Admin API: upload documents, rename, delete, manage per-investor releases
- Investor API: list released documents, stream download with audit log,
  upload own documents (max DATAROOM_MAX_UPLOAD_MB, default 50MB)
- /pitch-admin/dataroom: document list + release toggles + investor uploads tab
- /dataroom: investor-facing document library + upload section
- All reads and writes logged to pitch_audit_logs
- Migration 005: dataroom_documents, dataroom_releases, dataroom_investor_uploads
- AdminShell: Data Room nav link (FolderOpen icon)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pitch-deck/components/pitch-admin/AdminShell.tsx

@@ -10,6 +10,7 @@ import {
   TrendingUp,
   ShieldCheck,
   GitBranch,
+  FolderOpen,
   LogOut,
   Menu,
   X,
@@ -26,6 +27,7 @@ const NAV = [
   { href: '/pitch-admin/versions', label: 'Versions', icon: GitBranch },
   { href: '/pitch-admin/audit', label: 'Audit Log', icon: FileText },
   { href: '/pitch-admin/financial-model', label: 'Financial Model', icon: TrendingUp },
+  { href: '/pitch-admin/dataroom', label: 'Data Room', icon: FolderOpen },
   { href: '/pitch-admin/admins', label: 'Admins', icon: ShieldCheck },
 ]