Android: app shell + Custom Settings engine + Home Assistant integration

Generic settings architecture (data-driven, no per-setting UI code):
- SettingDefinition (id/name/description/category/type/default/min/max/
  choices/editable/sensitive/requiresRestart/visibleIf) x 8 types:
  boolean/string/number/select/multi-select/color/url/secret
- SettingsManager: validation, reset, custom CRUD, export/import
  (all-or-nothing with per-key rejection reasons; custom definitions
  travel in the export), secrets routed to EncryptedSharedPreferences
  (AndroidKeyStore master key) and excluded from export by default
- Settings screen renders controls from the type; search; add/edit/delete
  dialogs for custom settings; import/export dialogs
- Built-ins: General / Home Assistant / Appearance / Network / Advanced

Home Assistant integration (official REST + WebSocket APIs only):
- HomeAssistantClient: GET /api/, /api/states, /api/states/{id},
  POST /api/services/{domain}/{service}, WS /api/websocket
  (auth -> subscribe_events state_changed) with exponential-backoff
  reconnect; safe HaError types that never contain the token
- HaRepository: single service layer between UI and client; optimistic
  toggles reconciled by WS; poll fallback from refresh-interval setting
- Devices screen: discovery list, search, live states, toggles
  (light/switch/fan/input_boolean/humidifier)
- Cleartext permitted for LAN http:// URLs (same stance as the official
  HA companion app; TLS verification untouched); consent dialog on first
  launch; Record button present but inert until M4 (honest label)
- Tests: 29 unit tests (19 settings incl. secret routing, import
  validation, persistence; 10 HA via MockWebServer incl. 401 handling,
  unreachable, WS handshake + event + auth_invalid). All green.

Docs: docs/home-assistant.md (install, token creation, storage,
troubleshooting, endpoint table); README + ROADMAP updated honestly
(live e2e against a real HA server still in progress).

android/gradle.properties

@@ -0,0 +1,4 @@
+org.gradle.jvmargs=-Xmx3g -Dfile.encoding=UTF-8
+android.useAndroidX=true
+android.nonTransitiveRClass=true
+kotlin.code.style=official