fix(observability): gate global logs to admins, scope to managed containers, harden SSE (#1254)

* fix(observability): gate global logs to admins, scope to managed containers, harden SSE

Make the Logs feed an administrator view enforced on both sides (requireAdmin on
the /api/logs/global poll and SSE routes; the Logs nav item plus a redirect guard
on the frontend), and scope the feed to Sencho-managed containers only via a
shared isManagedByComposeDir helper that /stats now reuses.

Harden the SSE stream: a stateful frame demuxer that survives chunk boundaries so
a Docker frame split across reads is reassembled instead of dropped or garbled; a
per-stream error listener so one broken follow stream cannot crash the event loop
(it posts a single degraded notice and keeps the others alive); a cap on
concurrent follow streams with a truncation notice; a bounded initial tail; and
backpressure that pauses the source streams when the client is slow and resumes on
drain. Bound the polling snapshot's per-container fan-out with a concurrency limit.

Add process-local, in-memory log-stream counters exposed at the admin-only
/api/system/log-stream-metrics endpoint (active connections, lines streamed,
attach and frame errors). Collapse the view to the local hub and remove the dead
remote-node handling.

* fix(observability): close remote-proxy bypass of the global-logs admin gate

The logs feed's requireAdmin lives in the local route handler, which the remote
proxy skips when forwarding a request whose nodeId targets a remote node. A hub
user could therefore request /api/logs/global*, /api/logs/global/stream, or
/api/system/log-stream-metrics with x-node-id (or ?nodeId= for the SSE transport)
pointing at a remote node and have it served as the node-proxy admin on the far
side, sidestepping the gate entirely.

Add these paths to HUB_ONLY_PREFIXES so hubOnlyGuard rejects a remote nodeId with
403 before the proxy runs, matching the existing protection on audit-log,
scheduled-tasks, and notification-routes. Add regression tests covering the
collection path, the SSE sub-path (both the x-node-id header and the ?nodeId=
query transport), and the stream-metrics endpoint.

frontend/src/components/EditorLayout/__tests__/useViewNavigationState.test.tsx

@@ -38,6 +38,17 @@ function mockAdmiralAdmin() {
   } as unknown as ReturnType<typeof LicenseContext.useLicense>);
 }
 
+function mockCommunityAdmin() {
+  vi.mocked(AuthContext.useAuth).mockReturnValue({
+    isAdmin: true,
+    can: () => false,
+  } as unknown as ReturnType<typeof AuthContext.useAuth>);
+  vi.mocked(LicenseContext.useLicense).mockReturnValue({
+    isPaid: false,
+    license: null,
+  } as unknown as ReturnType<typeof LicenseContext.useLicense>);
+}
+
 function mockSkipperAdmin() {
   vi.mocked(AuthContext.useAuth).mockReturnValue({
     isAdmin: true,
@@ -199,20 +210,40 @@ describe('useViewNavigationState', () => {
 
   // ── navItems: community user ───────────────────────────────────────────────
 
-  it('navItems for community non-paid user contains base items only', () => {
+  it('navItems for community non-admin user contains base items only and hides admin-only Logs', () => {
     const { result } = renderHook(() => useViewNavigationState());
     const values = result.current.navItems.map(i => i.value);
     expect(values).toContain('dashboard');
     expect(values).toContain('fleet');
     expect(values).toContain('resources');
     expect(values).toContain('templates');
-    expect(values).toContain('global-observability');
+    // Logs is an admin-only operator view; a non-admin must not see the entry.
+    expect(values).not.toContain('global-observability');
     expect(values).not.toContain('auto-updates');
     expect(values).not.toContain('host-console');
     expect(values).not.toContain('audit-log');
     expect(values).not.toContain('scheduled-ops');
   });
 
+  it('shows the admin-only Logs entry for an admin on any tier (role gate, not tier gate)', () => {
+    mockCommunityAdmin();
+    const { result } = renderHook(() => useViewNavigationState());
+    expect(result.current.navItems.map(i => i.value)).toContain('global-observability');
+  });
+
+  it('redirects a non-admin off the Logs view when reached via a deep-link event', () => {
+    const onNavigateToDashboard = vi.fn();
+    // Community (non-admin) is the beforeEach default.
+    const { result } = renderHook(() => useViewNavigationState({ onNavigateToDashboard }));
+    act(() => {
+      window.dispatchEvent(
+        new CustomEvent(SENCHO_NAVIGATE_EVENT, { detail: { view: 'global-observability' } }),
+      );
+    });
+    expect(result.current.activeView).toBe('dashboard');
+    expect(onNavigateToDashboard).toHaveBeenCalled();
+  });
+
   // ── navItems: admiral admin ────────────────────────────────────────────────
 
   it('navItems for admiral paid admin contains all items', () => {