Standalone Shonar Desktop: vendor portable sources + local engine; decouple from ~/Projects/Shonar

- shared/ = portable Android-origin sources vendored from deferred/desktop-server
  (app/build.gradle.kts srcDir repointed; PlaybackController.kt excluded as Android-only)
- backend/ = bundled-lite engine (SQLite + inline queue); .venv symlinked from the
  old checkout, PYTHONPATH pins THIS backend's code over any editable install
- repoRoot() resolves this project dir (env SHONAR_REPO still wins); desktop-dev.sh
  watches shared/ + backend/
- Verified: :app:compileKotlin + :app:test green (23 tests); engine boots on :8010,
  self-migrates, /healthz ok

backend/shonar/api/v1/__init__.py

@@ -0,0 +1,25 @@
+"""API v1 router aggregation."""
+
+from fastapi import APIRouter
+
+from shonar.api.v1 import (
+    auth,
+    health,
+    models,
+    provider_info,
+    recordings,
+    search_exports,
+    users,
+)
+
+api_router = APIRouter(prefix="/api/v1")
+api_router.include_router(health.router)
+api_router.include_router(auth.router)
+api_router.include_router(users.router)
+api_router.include_router(recordings.router)
+api_router.include_router(models.router)
+api_router.include_router(provider_info.router)
+api_router.include_router(search_exports.router)
+
+# Included as later milestones land:
+# - tags (M9 follow-on)