feat: block self-stack lifecycle ops with UI and preflight guardrails (#1569)

* feat: block self-stack lifecycle ops with UI and preflight guardrails

Refuse update, deploy, down, stop, and delete when the stack matches Sencho's compose project.

Return 409 self_stack_protected. Expose isSelf on /statuses and disable guarded UI actions.

Add SelfStackProtectedDialog and self-managed-stack preflight warning.

Closes #1564

* fix: add missing stackSelfFlags mock to useSidebarContextMenu test

The production hook now reads stackListState.stackSelfFlags[file], but the
test mock did not include it, causing 6 tests to fail with TypeError:
Cannot read properties of undefined (reading 'web.yml').

* fix: harden self-stack protection during startup

Add a global environment preflight warning when Sencho is managed inside COMPOSE_DIR.

Align status decoration and route guards on Docker label fallback detection.

Block rollback and service-level stop on the protected self stack.

* fix: add self_stack_location to diagnostics-route expected check IDs

frontend/src/components/EditorLayout/ShellOverlays.tsx

@@ -2,6 +2,7 @@ import BashExecModal from '../BashExecModal';
 import { PolicyBlockDialog } from '../stack/PolicyBlockDialog';
 import { PreDeployScanDialog } from '../stack/PreDeployScanDialog';
 import { UpdateReadinessDialog } from '../stack/UpdateReadinessDialog';
+import { SelfStackProtectedDialog } from '../stack/SelfStackProtectedDialog';
 import { DeleteStackDialog } from './DeleteStackDialog';
 import { UnsavedChangesDialog } from './UnsavedChangesDialog';
 import { StackAlertSheet } from '../StackAlertSheet';
@@ -23,6 +24,8 @@ interface ShellOverlaysProps {
   stackName: string;
   gitSourceOpen: boolean;
   setGitSourceOpen: (open: boolean) => void;
+  canSelfUpdate: boolean;
+  onOpenFleetNodeUpdates: () => void;
 }
 
 export function ShellOverlays({
@@ -35,6 +38,8 @@ export function ShellOverlays({
   stackName,
   gitSourceOpen,
   setGitSourceOpen,
+  canSelfUpdate,
+  onOpenFleetNodeUpdates,
 }: ShellOverlaysProps) {
   const {
     deleteDialogOpen, closeDeleteDialog, stackToDelete,
@@ -45,6 +50,7 @@ export function ShellOverlays({
     policyBlock, setPolicyBlock, policyBypassing,
     updateReadiness, setUpdateReadiness,
     preDeployAdvisory,
+    selfStackProtectedOpen, setSelfStackProtectedOpen,
     stackMisconfigScanId, setStackMisconfigScanId,
     diffPreview, setDiffPreview, diffPreviewConfirming, setDiffPreviewConfirming,
   } = overlayState;
@@ -58,6 +64,13 @@ export function ShellOverlays({
         onConfirm={stackActions.deleteStack}
       />
 
+      <SelfStackProtectedDialog
+        open={selfStackProtectedOpen}
+        onOpenChange={setSelfStackProtectedOpen}
+        canOpenFleetUpdates={canSelfUpdate}
+        onOpenFleetUpdates={onOpenFleetNodeUpdates}
+      />
+
       <UnsavedChangesDialog
         open={!!pendingUnsavedLoad || !!pendingLeaveAction}
         onCancel={stackActions.cancelPendingUnsavedLoad}