feat: add Sis.Database module with openDatabase

src/Sis/Database.hs

@@ -0,0 +1,21 @@
+{- | SQLite database support for Sis.
+
+Opens (and creates if missing) a SQLite database with WAL journal
+mode and foreign keys enabled.
+-}
+module Sis.Database (
+    openDatabase,
+) where
+
+import Database.SQLite.Simple qualified as SQL
+
+-- | Open (or create) a SQLite database at the given path.
+--
+-- Enables WAL journal mode for concurrent read performance and
+-- enables foreign key enforcement.
+openDatabase :: FilePath -> IO SQL.Connection
+openDatabase path = do
+    conn <- SQL.open path
+    SQL.execute_ conn "PRAGMA journal_mode=WAL"
+    SQL.execute_ conn "PRAGMA foreign_keys=ON"
+    pure conn