fix: ensure data persistence across reinstallations

- Add entrypoint.sh: creates /app/data, stamps legacy DBs, runs alembic upgrade head
- Update Dockerfile to use new entrypoint and pre-create /app/data
- Change default DATABASE_URL to sqlite:///./data/dmarq.db
- Add _ensure_sqlite_dir() to database.py for automatic directory creation
- Update docker-compose.yml with app_data named volume for /app/data
- Add 6 tests for _ensure_sqlite_dir and updated default URL

Agent-Logs-Url: https://github.com/christianlouis/dmarq/sessions/2bac317b-97a2-450b-84f1-3e316f7ef54c

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

backend/app/core/config.py

@@ -23,7 +23,9 @@ class Settings(BaseSettings):
     API_V1_STR: str = "/api/v1"
 
     # Database
-    DATABASE_URL: str = "sqlite:///./dmarq.db"
+    # Default to a sub-directory so the SQLite file lives in a location that
+    # can be persisted via a Docker volume mount (e.g. /app/data).
+    DATABASE_URL: str = "sqlite:///./data/dmarq.db"
 
     # JWT Authentication
     SECRET_KEY: Optional[str] = None

backend/app/core/database.py

@@ -1,7 +1,9 @@
+import os
 from typing import Generator
 from urllib.parse import urlparse, urlunparse
 
 from sqlalchemy import create_engine
+from sqlalchemy.engine import make_url
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
 
@@ -30,10 +32,34 @@ def _make_sync_db_url(url: str) -> str:
     return urlunparse(parsed._replace(scheme=sync_scheme))
 
 
+def _ensure_sqlite_dir(url: str) -> None:
+    """Create the parent directory for a SQLite database file if needed.
+
+    For SQLite URLs (``sqlite:///relative/path`` or ``sqlite:////absolute/path``),
+    the parent directory must exist before SQLAlchemy tries to open (or create)
+    the file.  This is a no-op for in-memory databases (``sqlite://``) and for
+    non-SQLite URLs.
+    """
+    sa_url = make_url(url)
+    if not sa_url.drivername.startswith("sqlite"):
+        return
+    db_path = sa_url.database
+    if not db_path or db_path == ":memory:":
+        return  # in-memory – nothing to create
+    parent = os.path.dirname(db_path)
+    if parent:
+        os.makedirs(parent, exist_ok=True)
+
+
 settings = get_settings()
 
+_sync_url = _make_sync_db_url(settings.DATABASE_URL)
+
+# Ensure the parent directory exists before SQLAlchemy tries to open the file
+_ensure_sqlite_dir(_sync_url)
+
 # Configure SQLAlchemy (normalise async driver schemes to their sync equivalents)
-engine = create_engine(_make_sync_db_url(settings.DATABASE_URL), pool_pre_ping=True)
+engine = create_engine(_sync_url, pool_pre_ping=True)
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 
 # Create base class for SQLAlchemy models