Fix FileBrowser integration config lost after SyncFileBrowserMounts

SyncFileBrowserMounts regenerates config.yaml from scratch, overwriting
any integration config. The old approach used an async OnStackStart hook
after container restart, which failed due to timing issues (stack state
not yet refreshed).

New approach: ReapplyConfigForTarget() writes integration config
synchronously after config generation but before container restart,
with a no-op RestartStack since the caller handles restart.

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

controller/internal/web/handlers.go

@@ -1605,6 +1605,11 @@ func (s *Server) SyncFileBrowserMounts() {
 		return
 	}
 
+	// Re-apply active integrations into config.yaml (before container restart)
+	if s.integrationMgr != nil {
+		s.integrationMgr.ReapplyConfigForTarget("filebrowser")
+	}
+
 	// Generate and write compose (includes config.yaml mount)
 	compose := generateFileBrowserCompose(domain, storageMounts)
 	if err := os.WriteFile(composePath, []byte(compose), 0644); err != nil {
@@ -1621,10 +1626,6 @@ func (s *Server) SyncFileBrowserMounts() {
 		s.logger.Printf("[ERROR] Failed to recreate FileBrowser: %s — %v", string(out), err)
 	} else {
 		s.logger.Printf("[INFO] FileBrowser mounts synced — %d storage path(s), config updated", len(paths))
-		// Re-apply active integrations (config regeneration overwrites config.yaml)
-		if s.integrationMgr != nil {
-			go s.integrationMgr.OnStackStart(context.Background(), "filebrowser")
-		}
 	}
 }