feat: add changelog and versioning, surface it in admin

Bumps version to 0.2.0 (root + apps/web package.json) and adds
CHANGELOG.md as the canonical human-readable history, mirrored by
apps/web/lib/changelog.ts as the in-app data source (single
ChangelogList component renders both).

- /changelog: user-facing page, linked from the account dropdown.
- /admin/changelog: same list, plus a "Version" card on the admin
  overview dashboard linking to it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/app/admin/layout.tsx

@@ -3,7 +3,7 @@ import { headers } from "next/headers";
 import { auth } from "@/lib/auth/server";
 import { db, users, eq } from "@epicure/db";
 import Link from "next/link";
-import { Shield, Users, BookOpen, Settings, BarChart3, ClipboardList, HardDrive, Bot, ArrowLeft, Gauge, Mail, Flag } from "lucide-react";
+import { Shield, Users, BookOpen, Settings, BarChart3, ClipboardList, HardDrive, Bot, ArrowLeft, Gauge, Mail, Flag, History } from "lucide-react";
 import { cn } from "@/lib/utils";
 
 const adminNav = [
@@ -17,6 +17,7 @@ const adminNav = [
   { href: "/admin/storage", label: "Storage", icon: HardDrive },
   { href: "/admin/ai-config", label: "AI Config", icon: Bot },
   { href: "/admin/settings", label: "Settings", icon: Settings },
+  { href: "/admin/changelog", label: "Changelog", icon: History },
 ];
 
 export default async function AdminLayout({ children }: { children: React.ReactNode }) {