Fix FB integration not picked up + OO mixed content behind HTTPS proxy

- SyncFileBrowserMounts: use --force-recreate so FB always picks up
  config.yaml changes (bind mount not detected by docker compose up)
- OnlyOffice compose template: add Traefik middleware to forward
  X-Forwarded-Proto=https (fixes mixed content errors in browser)
- Nextcloud handler: add StorageUrl=http://nextcloud for internal
  file download callbacks from OO Document Server

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

controller/internal/web/handlers.go

@@ -1620,7 +1620,7 @@ func (s *Server) SyncFileBrowserMounts() {
 	// Recreate container — H16: use 60s timeout to prevent hanging indefinitely.
 	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
 	defer cancel()
-	cmd := exec.CommandContext(ctx, "docker", "compose", "up", "-d", "--remove-orphans")
+	cmd := exec.CommandContext(ctx, "docker", "compose", "up", "-d", "--force-recreate", "--remove-orphans")
 	cmd.Dir = stackDir
 	if out, err := cmd.CombinedOutput(); err != nil {
 		s.logger.Printf("[ERROR] Failed to recreate FileBrowser: %s — %v", string(out), err)