refactor: establish database migration foundation

database.py

@@ -6,6 +6,8 @@ from datetime import datetime, timezone
 from pathlib import Path
 from typing import Any
 
+from backend.database import MIGRATIONS, MigrationRunner, SQLiteConnectionFactory
+
 
 def _optional_float(value: Any) -> float | None:
     if value in (None, ""):
@@ -16,28 +18,15 @@ def _optional_float(value: Any) -> float | None:
         return None
 
 
-class ManagedConnection(sqlite3.Connection):
-    """Commit or roll back, then release the SQLite file handle on context exit."""
-
-    def __exit__(self, exc_type, exc_value, traceback):
-        try:
-            return super().__exit__(exc_type, exc_value, traceback)
-        finally:
-            self.close()
-
-
 class ReviewDatabase:
     def __init__(self, path: Path) -> None:
         self.path = path
         self.path.parent.mkdir(parents=True, exist_ok=True)
+        self.connection_factory = SQLiteConnectionFactory(self.path)
         self._initialize()
 
     def connect(self) -> sqlite3.Connection:
-        connection = sqlite3.connect(self.path, timeout=20, factory=ManagedConnection)
-        connection.row_factory = sqlite3.Row
-        connection.execute("PRAGMA journal_mode=WAL")
-        connection.execute("PRAGMA foreign_keys=ON")
-        return connection
+        return self.connection_factory.connect()
 
     def _initialize(self) -> None:
         with self.connect() as connection:
@@ -656,6 +645,7 @@ class ReviewDatabase:
                 ON screener_runs(user_id, mode, trade_date DESC, id DESC)
                 """
             )
+            MigrationRunner().apply(connection, MIGRATIONS)
 
     def count_users(self) -> int:
         with self.connect() as connection: