fix(phase3): fix database/device access in search, backup, stats, map endpoints

- Search, backup, stats endpoints used current_app.config.get('DEVICE_MANAGER')
  which doesn't exist — replaced with _get_dm()/_get_db() helpers
- /api/device/info used old v1 CLI — replaced with DeviceManager.get_device_info()
  returning structured dict instead of string (fixes map own device marker)
- Moved search button from navbar to FAB menu (between filter and DM buttons)
- Bump SW cache to v7

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

app/static/css/style.css

@@ -1240,6 +1240,12 @@ main {
     color: white;
 }
 
+/* Search FAB button (orange gradient) */
+.fab-search {
+    background: linear-gradient(135deg, #fd7e14 0%, #e8590c 100%);
+    color: white;
+}
+
 /* Filter bar overlay - slides down from top of chat area */
 .filter-bar {
     position: absolute;