Add `GET /api/v1/instance/languages` to REST API (#24443)

Co-authored-by: Eugen Rochko <eugen@zeonfederated.com>
Co-authored-by: Claire <claire.github-309c@sitedethib.com>

Refactor: replace whitelist_mode mentions with limited_federation_mode (#26252)

Add List-Unsubscribe email header (#26085)

Migrate to request specs in `/api/v2/filters` (#25721)

Coverage for `Auth::OmniauthCallbacks` controller (#26147)

Fix CSP headers being unintendedly wide (#26105)

Wrong count in response when removing favourite/reblog (#24365)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

Migrate to request specs in `/api/v1/mutes` (#25622)

Migrate to request specs in `/api/v1/bookmarks` (#25520)

Migrate to request specs in `/api/v1/timelines/public` (#25746)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

Migrate to request specs in `/api/v1/statuses/:status_id/favourite` (#25626)

Migrate to request specs in `/api/v1/statuses/:status_id/bookmark` (#25624)

Migrate to request specs in `/api/v1/polls` (#25596)

Migrate to request specs in `/api/v1/statuses/:status_id/pin` (#25635)

Migrate to request specs in `/api/v1/emails/confirmations` (#25686)

Migrate to request specs in `/api/v1/timelines/home` (#25743)

Fix embed dropdown menu item for unauthenticated users (#25964)

Fix processing of media files with unusual names (#25788)

Migrate to request specs in `/api/v1/suggestions` (#25540)

Migrate to request specs in `/api/v1/admin/account_actions` (#25514)