feat: enhance all frontend management views
Dashboard (RCA-15):
- Stats cards: server status, devices (online/offline breakdown), cookies
by domain count, WebSocket connections
- Device status table with online badges
- Quick action cards linking to cookies, devices, settings
Cookies (RCA-16):
- Domain-grouped collapsible list with expand/collapse
- Search by domain or cookie name
- Right-side detail panel showing all cookie fields (Headless UI transition)
- Checkbox selection + batch delete
- Per-cookie inline delete
Devices (RCA-17):
- Card grid with platform icons (CH/FF/ED/SA), online/offline badges
- Status filter tabs (All/Online/Offline)
- Expandable details (full device ID, platform, registration date)
- Two-step revoke confirmation dialog inline
Settings (RCA-18):
- Headless UI Tab component with 3 tabs: Sync, Security, Appearance
- Sync: auto-sync toggle, frequency selector (real-time/1m/5m/manual)
- Security: change password form, max devices
- Appearance: theme picker (light/dark/system), language selector
- Save with success toast notification
Co-Authored-By: Paperclip <noreply@paperclip.ing>
147f9d4761