Implement quick-add registry (task 21)

- Add url field to QuickAddAction; make action optional
- Add getQuickAdds() + SerializedQuickAddItem to registry so quick-add
  data can cross the server→client RSC boundary without serializing fns
- Update calendar/lists/notes manifests with navigation URLs
- QuickAddProvider wraps root layout: holds sheet/palette open state and
  global cmd/ctrl+k shortcut
- QuickAddSheet: bottom drawer on mobile, right-side popover on desktop,
  actions grouped by module
- CommandPalette: cmdk-powered modal with fuzzy filter and full keyboard
  nav (arrows + enter + esc)
- QuickAddFab: client button replacing the plain + stub in the dashboard
- Add .claude/** to ESLint ignores to prevent stale worktree artifacts
  from failing lint

All 4 E2E specs pass; typecheck, lint, and build clean.

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

src/app/page.tsx

@@ -6,6 +6,7 @@ import { getCurrentSession } from "@/lib/session";
 import { getWidget } from "@/modules/_core";
 import { users } from "@/modules/_core/schema";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
+import { QuickAddFab } from "@/components/quick-add-fab";
 
 // Static lookup ensures Tailwind sees all sm:col-span-* classes at build time.
 const smColSpan: Record<number, string> = {
@@ -43,13 +44,7 @@ export default async function DashboardPage() {
     <div className="p-4 sm:p-6">
       <div className="mb-6 flex items-center justify-between">
         <h1 className="text-2xl font-bold">Dashboard</h1>
-        {/* Quick-add FAB — wired up in task 21 */}
-        <button
-          aria-label="Quick add"
-          className="flex h-10 w-10 items-center justify-center rounded-full bg-primary text-primary-foreground shadow-md transition-opacity hover:opacity-90"
-        >
-          <span className="text-xl leading-none">+</span>
-        </button>
+        <QuickAddFab />
       </div>
 
       <div className="grid grid-cols-1 gap-4 sm:grid-cols-12">