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/health.py

@@ -0,0 +1,65 @@
+"""Health and system endpoints."""
+
+from __future__ import annotations
+
+import time
+
+from fastapi import APIRouter
+from sqlalchemy import text
+
+from shonar.api.deps import SessionDep
+from shonar.core.config import get_settings
+
+router = APIRouter(tags=["health"])
+
+_STARTED = time.monotonic()
+
+
+@router.get("/healthz")
+async def healthz() -> dict:
+    """Liveness: process up. No auth, no dependencies."""
+    return {"status": "ok", "uptime_seconds": round(time.monotonic() - _STARTED, 1)}
+
+
+@router.get("/readyz")
+async def readyz(session: SessionDep) -> dict:
+    """Readiness: database reachable. Config warnings surfaced for admins
+    via /api/v1/system/status instead of failing readiness."""
+    try:
+        await session.execute(text("SELECT 1"))
+        db_ok = True
+    except Exception:
+        db_ok = False
+    status_code_body = {"status": "ok" if db_ok else "degraded", "database": db_ok}
+    return status_code_body
+
+
+@router.get("/system/status")
+async def system_status() -> dict:
+    """Public-ish status: which AI features are enabled (never any secrets).
+    The app uses this to show honest AI-processing state to users."""
+    settings = get_settings()
+    return {
+        "app": settings.app_name,
+        "registration_enabled": settings.allow_registration,
+        "ai": {
+            "transcription_provider": settings.transcription_provider,
+            "transcription_enabled": settings.transcription_provider != "none",
+            "llm_provider": settings.llm_provider,
+            "llm_enabled": settings.llm_provider != "none",
+            # Explicit disclosure: are any external (non-local) calls made?
+            "external_ai_in_use": (
+                settings.transcription_provider == "whisper_http"
+                and "localhost" not in settings.transcription_base_url
+                and "127.0.0.1" not in settings.transcription_base_url
+            )
+            or (
+                settings.llm_provider == "openai_compat"
+                and "localhost" not in settings.llm_base_url
+                and "127.0.0.1" not in settings.llm_base_url
+            ),
+        },
+        "storage_backend": settings.storage_backend,
+        "audio_conversion_enabled": settings.audio_conversion_enabled,
+        "config_warnings": settings.validate_production(),
+    }