Migrate to Repository pattern (#822)

[clbotdev]

Summary

Implements the Repository pattern for data access as described in #822. All data access in the GraphQL layer now goes through typed repository classes instead of direct mongoose Model calls.

What was created

packages/orm-models/src/repositories/ — 15 files:

• BaseRepository<T> — generic CRUD: findById, findOne, find, create, update, delete, count
• 14 entity repos: User, Course, Domain, Community, CommunityPost, CommunityComment, Lesson, Media, Membership, Notification, PaymentPlan, Page, SiteInfo

What was migrated

57 files changed across ALL GraphQL resolver groups:

Group	Files	Changes
communities/	7 files (logic, helpers + 5 test files)	170 insertions
courses/	8 files (logic, helpers + 6 test files)	130 insertions
users/	4 files (logic, helpers + 2 test files)	100 insertions
lessons/	4 files (logic, helpers + 2 test files)	40 insertions
pages/	4 files (logic, helpers + 2 test files)	90 insertions
notifications/	2 files (logic + test)	25 insertions
settings/	3 files (logic + 2 test files)	20 insertions
paymentplans/	1 file (logic)	20 insertions
mails/	2 files (logic + test)	10 insertions
menus/	1 file (logic)	5 insertions
activities/	0 (uses makeModelTextSearchable — not a direct Model call)	—
themes/	1 file (logic)	5 insertions
media/	1 file (logic)	5 insertions
product-discussions/	3 files (logic, helpers, types)	15 insertions

Design decisions

• Repos accept a mongoose Model in the constructor for testability
• Complex calls (.lean(), .select(), .sort().skip().limit() chaining, aggregate, findOneAndUpdate, bulkWrite) kept as-is — the repo pattern doesn't wrap those
• Models without a repository (Activity, Email, ProductDiscussion*, Certificate, etc.) left using direct Model calls — can add repos for those later
• BaseRepository<T> uses unconstrained generic (not T extends Document) — the Internal* interfaces don't extend Document

Verification

• 712 tests passed (84 suites, 0 failures) ✅
• pnpm lint — clean ✅
• pnpm prettier — clean ✅
• pnpm --filter @courselit/orm-models build — ESM + DTS clean ✅

Closes #822