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/EditorView.tsx

@@ -189,6 +189,8 @@ export interface EditorViewProps {
 
     // Composed action: wraps setStackToDelete + setDeleteDialogOpen
     requestDeleteStack: () => void;
+    /** True when this stack is the running Sencho instance on the active node. */
+    isSelfStack?: boolean;
 
     // Recovery surface for a failed/stalled operation on this stack (undefined
     // when the last op succeeded or none has run). onRefreshState re-syncs
@@ -270,6 +272,7 @@ export function EditorView(props: EditorViewProps) {
         setGitSourceOpen,
         setCopiedDigest,
         requestDeleteStack,
+        isSelfStack,
         recoveryResult,
         onRefreshState,
         onDismissRecovery,
@@ -381,6 +384,7 @@ export function EditorView(props: EditorViewProps) {
                                         rollbackStack={rollbackStack}
                                         scanStackConfig={scanStackConfig}
                                         requestDeleteStack={requestDeleteStack}
+                                        isSelfStack={isSelfStack}
                                         stackMuteActions={stackMuteActions}
                                     />
                                 </div>