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/adapters/webdav_adapter.rs

@@ -120,6 +120,62 @@ pub enum LockType {
     Write,
 }
 
+/// Extra property context for Nextcloud/ownCloud WebDAV extensions.
+#[derive(Debug, Clone)]
+pub struct NextcloudPropContext {
+    pub file_id: Option<i64>,
+    pub oc_id: Option<String>,
+    pub owner_id: Option<String>,
+    pub owner_display_name: Option<String>,
+    pub permissions: String,
+    pub size: u64,
+    pub has_preview: bool,
+    pub is_encrypted: bool,
+    pub mount_type: String,
+    pub contained_file_count: u64,
+    pub contained_folder_count: u64,
+}
+
+impl NextcloudPropContext {
+    pub fn for_folder(
+        file_id: Option<i64>,
+        oc_id: Option<String>,
+        owner: &str,
+        contained_files: u64,
+        contained_folders: u64,
+    ) -> Self {
+        Self {
+            file_id,
+            oc_id,
+            owner_id: Some(owner.to_string()),
+            owner_display_name: Some(owner.to_string()),
+            permissions: "RGDNVCK".to_string(),
+            size: 0,
+            has_preview: false,
+            is_encrypted: false,
+            mount_type: "dir".to_string(),
+            contained_file_count: contained_files,
+            contained_folder_count: contained_folders,
+        }
+    }
+
+    pub fn for_file(file_id: Option<i64>, oc_id: Option<String>, owner: &str, size: u64) -> Self {
+        Self {
+            file_id,
+            oc_id,
+            owner_id: Some(owner.to_string()),
+            owner_display_name: Some(owner.to_string()),
+            permissions: "RGDNVW".to_string(),
+            size,
+            has_preview: false,
+            is_encrypted: false,
+            mount_type: "file".to_string(),
+            contained_file_count: 0,
+            contained_folder_count: 0,
+        }
+    }
+}
+
 /// WebDAV adapter for converting between XML and domain objects
 pub struct WebDavAdapter;