feat(nextcloud): add Nextcloud-compatible API layer

Implement a complete Nextcloud client compatibility layer so that
Nextcloud desktop/mobile sync clients can connect to OxiCloud.

Key additions:
- Login Flow v2 (device auth) with OIDC bridge support
- WebDAV handler compatible with Nextcloud clients (PROPFIND, GET,
  PUT, DELETE, MKCOL, MOVE, COPY, HEAD, PROPPATCH)
- OCS API endpoints (user info, capabilities, notifications stubs,
  sharees, unified search)
- Basic Auth middleware with app password verification, account
  lockout integration, and blake3-keyed auth cache
- App password management: create, list, revoke via both native
  API (JWT-authenticated profile page) and Nextcloud OCS endpoints
- Nextcloud file ID mapping (oc:fileid) with persistent DB storage
- Chunked upload support (Nextcloud v2 chunking protocol)
- Trashbin WebDAV interface
- Avatar (SVG placeholder) and preview (redirect) handlers
- User profile page with app password management UI
- URL user validation on all DAV routes (403 on mismatch)
- Database schema for app_passwords and nextcloud_object_ids tables

All services are behind a `nextcloud.enabled` config flag and
cleanly separated under src/interfaces/nextcloud/.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/infrastructure/repositories/pg/mod.rs

@@ -7,6 +7,7 @@ mod contact_persistence_dto;
 mod contact_pg_repository;
 mod device_code_pg_repository;
 mod favorites_pg_repository;
+mod nextcloud_object_id_repository;
 mod recent_items_pg_repository;
 mod session_pg_repository;
 mod settings_pg_repository;
@@ -32,6 +33,7 @@ pub use favorites_pg_repository::FavoritesPgRepository;
 pub use file_blob_read_repository::FileBlobReadRepository;
 pub use file_blob_write_repository::FileBlobWriteRepository;
 pub use folder_db_repository::FolderDbRepository;
+pub use nextcloud_object_id_repository::NextcloudObjectIdRepository;
 pub use recent_items_pg_repository::RecentItemsPgRepository;
 pub use session_pg_repository::SessionPgRepository;
 pub use settings_pg_repository::SettingsPgRepository;