refactor: inject the database into services via a constructor

Pilot on the categories service: a CategoriesService class holds the Drizzle
handle, and services/index.ts wires the real instance once for the server while
tests build their own on an in-memory database. AppDatabase moves from
groceries.ts to db/types.ts.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/lib/server/services/index.ts b/src/lib/server/services/index.ts
new file mode 100644
index 0000000..25a05be
--- /dev/null
+++ b/src/lib/server/services/index.ts
@@ -0,0 +1,8 @@
+import { db } from '$lib/server/db';
+import { CategoriesService } from './categories';
+
+/**
+ * Services wired once for the running server. Tests build their own instances
+ * with a test database instead of importing from here.
+ */
+export const categoriesService = new CategoriesService(db);