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/tests/test_health.py

@@ -0,0 +1,29 @@
+"""Health-check and system-status tests."""
+
+
+async def test_healthz(client):
+    r = await client.get("/api/v1/healthz")
+    assert r.status_code == 200
+    body = r.json()
+    assert body["status"] == "ok"
+    assert body["uptime_seconds"] >= 0
+
+
+async def test_readyz_with_db(client):
+    r = await client.get("/api/v1/readyz")
+    assert r.status_code == 200
+    assert r.json() == {"status": "ok", "database": True}
+
+
+async def test_system_status_reports_ai_state_honestly(client):
+    r = await client.get("/api/v1/system/status")
+    assert r.status_code == 200
+    body = r.json()
+    # Default test config: AI disabled, no external calls.
+    assert body["ai"]["transcription_enabled"] is False
+    assert body["ai"]["llm_enabled"] is False
+    assert body["ai"]["external_ai_in_use"] is False
+    # No secrets ever present in the public status payload.
+    body_text = r.text.lower()
+    for leak in ("api_key", "password", "secret_key"):
+        assert leak not in body_text