feat(pitch-deck): full pitch versioning with git-style history (#4)

Full pitch versioning: 12 data tables versioned as JSONB snapshots,
git-style parent chain (draft→commit→fork), per-investor assignment,
side-by-side diff engine, version-aware /api/data + /api/financial-model.

Bug fixes: FM editor [object Object] for JSONB arrays, admin scroll.

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

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

@@ -9,6 +9,7 @@ import {
   FileText,
   TrendingUp,
   ShieldCheck,
+  GitBranch,
   LogOut,
   Menu,
   X,
@@ -22,6 +23,7 @@ interface AdminShellProps {
 const NAV = [
   { href: '/pitch-admin', label: 'Dashboard', icon: LayoutDashboard, exact: true },
   { href: '/pitch-admin/investors', label: 'Investors', icon: Users },
+  { 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/admins', label: 'Admins', icon: ShieldCheck },
@@ -43,7 +45,7 @@ export default function AdminShell({ admin, children }: AdminShellProps) {
   }
 
   return (
-    <div className="min-h-screen bg-[#0a0a1a] text-white flex">
+    <div className="h-screen bg-[#0a0a1a] text-white flex overflow-hidden">
       {/* Sidebar */}
       <aside
         className={`fixed lg:static inset-y-0 left-0 z-40 w-64 bg-black/40 backdrop-blur-xl border-r border-white/[0.06]
@@ -111,7 +113,7 @@ export default function AdminShell({ admin, children }: AdminShellProps) {
       )}
 
       {/* Main content */}
-      <div className="flex-1 flex flex-col min-w-0">
+      <div className="flex-1 flex flex-col min-w-0 min-h-0">
         <header className="lg:hidden flex items-center justify-between px-4 py-3 border-b border-white/[0.06]">
           <button
             onClick={() => setOpen(true)}