chore: switch to all-SQLite stack (drop Postgres service)

.env.example

@@ -1,12 +1,14 @@
 # Copy to `.env` and fill in values. `.env` is gitignored.
 FORGEJO_TOKEN=
 
-# --- databases (compose service `db`) ---
-POSTGRES_USER=kirche
-POSTGRES_PASSWORD=
-POSTGRES_DB=kirche_einfach
-DATABASE_URL=postgresql+psycopg://kirche:<password>@db:5432/kirche_einfach
-TEST_DATABASE_URL=postgresql+psycopg://kirche:<password>@db:5432/kirche_einfach_test
+# --- app database (SQLite, default if unset) ---
+# Override only if you want a different engine/URL.
+# DATABASE_URL=sqlite:///backend/data/kirche.db
+
+# --- canonical flow definitions ---
+# FLOWS_DIR=backend/flows
+# Auto-reconcile backend/flows into DB + LFX while the API runs.
+# FLOWS_WATCH_ENABLED=true
 
 # --- langflow (authoring, dev only) ---
 LANGFLOW_URL=http://langflow:7860
@@ -15,7 +17,7 @@ LANGFLOW_SUPERUSER_PASSWORD=
 LANGFLOW_SECRET_KEY=
 # Single static key; validated against env (LANGFLOW_API_KEY_SOURCE=env), superuser scope.
 LANGFLOW_API_KEY=sk-
-LANGFLOW_DATABASE_URL=postgresql://kirche:<password>@db:5432/langflow
+# Langflow stores flows in its own SQLite file when unset.
 
 # --- lfx (flow runtime) ---
 LFX_URL=http://lfx:6004
@@ -25,4 +27,4 @@ LFX_API_KEY=lfx-
 CALLBACK_BASE_URL=http://app:8000
 
 # --- LLM (optional; tests mock the provider without it) ---
-# LLM_API_KEY=
+# LLM_API_KEY=