tenseleyflow/shithub / eee1397

+- **REST: followers / following (S50 §17).**

+  `GET /api/v1/users/{username}/followers` and

+  `GET /api/v1/users/{username}/following` (both paginated;

+  `Link:` headers), plus the authenticated-user-scoped

+  `GET /api/v1/user/following/{target}` (204/404 membership

+  probe matching gh), `PUT /api/v1/user/following/{target}`

+  (follow), and `DELETE` (unfollow). Self-follow returns 422.

+  Reuses `internal/social.FollowUser` / `UnfollowUser` so the

+  follow rate-limit and `followed_user` domain event stay in

+  one place. Org-follow variants remain on the HTML surface.

+- **Capability:** `followers` added to `/api/v1/meta`.