feat: app-to-app integration framework + OnlyOffice handlers

Generic integration system for connecting deployed apps via toggle UI.
First handlers: OnlyOffice→FileBrowser (config.yaml patch) and
OnlyOffice→Nextcloud (occ CLI). Lifecycle hooks auto-suspend on
stop and re-apply on start.

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

controller/cmd/controller/main.go

@@ -23,6 +23,7 @@ import (
 	cf "gitea.dooplex.hu/admin/felhom-controller/internal/cloudflare"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/crypto"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/config"
+	"gitea.dooplex.hu/admin/felhom-controller/internal/integrations"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/metrics"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/monitor"
 	"gitea.dooplex.hu/admin/felhom-controller/internal/notify"
@@ -647,9 +648,15 @@ func main() {
 		logger.Printf("[INFO] Geo-restriction support enabled (CF API token configured)")
 	}
 
+	// --- Initialize integration manager ---
+	integrationStacks := &integrationStackAdapter{mgr: stackMgr}
+	integrationMgr := integrations.NewManager(sett, integrationStacks, cfg.Customer.Domain, cfg.Paths.StacksDir, encKey, logger)
+	apiRouter.SetIntegrationManager(integrationMgr)
+
 	// --- Initialize web server ---
 	webServer := web.NewServer(cfg, stackMgr, cpuCollector, backupMgr, crossDriveRunner, sched, sett, alertMgr, notifier, updater, logger, Version)
 	webServer.SetEncryptionKey(encKey)
+	webServer.SetIntegrationManager(integrationMgr)
 	webServer.SetStorageWatchdog(storageWatchdog)
 	if assetsSyncer != nil {
 		webServer.SetAssetsSyncer(assetsSyncer)
@@ -917,6 +924,23 @@ func (a *stackAdapter) GetStackHDDPath(name string) string {
 	return ""
 }
 
+// integrationStackAdapter implements integrations.StackProvider using stacks.Manager.
+type integrationStackAdapter struct {
+	mgr *stacks.Manager
+}
+
+func (a *integrationStackAdapter) GetStack(name string) (*stacks.Stack, bool) {
+	return a.mgr.GetStack(name)
+}
+
+func (a *integrationStackAdapter) GetStacks() []stacks.Stack {
+	return a.mgr.GetStacks()
+}
+
+func (a *integrationStackAdapter) RestartStack(name string) error {
+	return a.mgr.RestartStack(name)
+}
+
 // geoStackAdapter implements cloudflare.StackLister for geo-restriction sync.
 type geoStackAdapter struct {
 	mgr    *stacks.Manager