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, 5 insertions, 0 deletions

diff --git a/src/lib/server/db/types.ts b/src/lib/server/db/types.ts
new file mode 100644
index 0000000..d842677
--- /dev/null
+++ b/src/lib/server/db/types.ts
@@ -0,0 +1,5 @@
+import type { LibSQLDatabase } from 'drizzle-orm/libsql';
+import type * as schema from './schema';
+
+/** The Drizzle handle a service is built with. */
+export type AppDatabase = LibSQLDatabase<typeof schema>;