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/application/services/file_upload_service.rs

@@ -182,9 +182,11 @@ impl FileUploadUseCase for FileUploadService {
         content: &[u8],
         content_type: &str,
     ) -> Result<FileDto, DomainError> {
+        // Look up the folder ID by folder path
         let parent_id = if !parent_path.is_empty() {
             if let Some(file_read) = &self.file_read {
-                file_read.get_parent_folder_id(parent_path).await.ok()
+                // Use get_folder_id_by_path to look up the folder directly
+                file_read.get_folder_id_by_path(parent_path).await.ok()
             } else {
                 None
             }