feat(zeta): add mobile_app component to Home Assistant

Enables iOS companion app access.

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

Author: stackptr

hosts/zeta/services/home-assistant.nix

@@ -12,6 +12,7 @@
       "radio_browser"
       # Required by ai_task → camera import chain in service descriptions
       "camera"
+      "mobile_app"
     ];
     config = {
       http = {