Add MDI icon picker to all entity types

- Install @mdi/js (~7000 Material Design Icons)
- IconPicker component: dropdown with search, popular icons grid,
  clear option. Stores icon name as string (e.g. "mdiCamera")
- MdiIcon component: renders SVG from icon name
- Backend: add `icon` field to ImmichServer, TelegramBot,
  TrackingConfig, TemplateConfig, NotificationTarget, AlbumTracker
- All 6 entity pages: icon picker next to name input in create/edit
  forms, icon displayed on entity cards

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

frontend/package.json

@@ -27,5 +27,8 @@
 		"tailwindcss": "^4.2.2",
 		"typescript": "^5.9.3",
 		"vite": "^7.3.1"
+	},
+	"dependencies": {
+		"@mdi/js": "^7.4.47"
 	}
 }