feat(db): move auth schema into Drizzle structure and add user FK

- Move auth schema from auth-schema.ts to lib/db/schema/auth.ts
- Export auth tables (user, session, account, verification, passkey) via barrel
- Add FK from performanceEntries.userId to user.id
- Generate and apply migration for auth tables + user FK
- Remove unused echarts dependency

lib/db/schema/index.ts

@@ -1,4 +1,5 @@
 // Barrel export — will be populated as schema files are created
+export * from "./auth"
 export * from "./games"
 export * from "./gameVersions"
 export * from "./hardware"