Add /email route as standalone web email client; v1.1.11

Extracts the email inbox from /admin and builds it as a full-viewport
email client at /email with the same admin auth. Key improvements over
the old embedded panel:

- Full-height split-pane layout (sidebar list + detail pane)
- Subject line extracted and shown separately for inbound emails
- Inline reply composer inside the detail pane (no more page-jump)
- Compose-new button for outbound messages to arbitrary addresses
- Search/filter across name, email, subject, and body
- Unread dot indicators with localStorage tracking (marks read on open)
- Keyboard navigation: ↑/↓ or j/k to move, r to reply, e to archive, Esc to close
- Source badges (contact-form / inbound-email) on list items
- Sent history and reply templates accessible via footer drawers
- 30-second polling for new messages
- New POST /api/admin-email/compose server endpoint for outbound sends
- Dashboard card "Open Inbox" now links to /email

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

package.json

@@ -1,7 +1,7 @@
 {
   "name": "siteforge",
   "private": true,
-  "version": "1.1.10",
+  "version": "1.1.11",
   "type": "module",
   "scripts": {
     "dev": "vite",