feat(wopi): add WOPI protocol support for collaborative editing

Implement the Web Application Open Platform Interface (WOPI) protocol
to enable collaborative document editing with Collabora Online and
OnlyOffice through OxiCloud.

Backend:
- WOPI token service with HMAC-SHA256 signed access tokens
- WOPI lock service with in-memory lock management and expiry
- WOPI discovery service for auto-detecting editor capabilities
- WOPI HTTP handler: CheckFileInfo, GetFile, PutFile, Lock/Unlock
- File entity extended with owner_id for WOPI file-info responses
- Configuration via WOPI_* environment variables
- Services wired through DI in AppState

Frontend:
- WOPI editor component with modal and new-tab viewing modes
- Context menu integration for opening files in online editors
- Inline viewer integration for document preview

Infrastructure:
- Docker Compose file for local Collabora/OnlyOffice dev setup

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

static/js/features/files/inlineViewer.js

@@ -90,6 +90,13 @@ class InlineViewer {
   
   openFile(file) {
     console.log('Opening file:', file);
+
+    // WOPI editor intercept: open Office documents in the WOPI editor
+    if (window.wopiEditor && window.wopiEditor.canEdit(file.name)) {
+        window.wopiEditor.openInModal(file.id, file.name, 'edit');
+        return;
+    }
+
     this.currentFile = file;
     
     // Get container