M0: toolchain, monorepo scaffold, gateway plugin skeleton, CMP app

- gateway-plugin/: android platform plugin (plugin.yaml + adapter.py
  register(ctx) + no-op AndroidAdapter) + stub modules for M1-M5
- app/: Compose Multiplatform project (shared KMP + androidApp +
  desktopApp) with Gradle wrapper; builds :androidApp:assembleDebug
  and :desktopApp:compileKotlin
- scripts/guard_hermes_agent.sh + pre-commit hook: fail if hermes-agent/
  is staged (read-only reference, never committed)
- .gitignore excludes hermes-agent/; docs/ reference library

gateway-plugin/outbox.py

@@ -0,0 +1,10 @@
+"""SQLite offline outbox + monotonic sync cursor.
+
+Undelivered frames are appended per ``chat_id`` with a monotonic cursor so a
+reconnecting app can ``sync {cursor}`` the delta without re-reading full
+history. Retention prunes old entries (``outbox_retention_hours``).
+
+Storage: ``get_hermes_home()/"android"/outbox.db``.
+
+Milestone M3 (built), extended in M5 (push integration).
+"""