Fix Check All timeout and remove last dashboard fallback data

Advisory sources:
- Replace batch /check endpoint call (504 timeout after 30s for 42+
  sources) with parallel individual checks in batches of 6. Progress
  indicator now shows live "Checking (N/M)..." as each source completes.
  Verified: 54/55 sources healthy on fresh install.

Dashboard:
- Remove the 5-element fallbackEnvironments array that was still
  rendering fake environment cards. Empty array now correctly triggers
  the setup guide on installs without PlatformContextStore environments.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Web/StellaOps.Web/src/app/features/integrations/advisory-vex-sources/advisory-source-catalog.component.ts

@@ -14,6 +14,7 @@ import {
   SourceStatusItem,
   SourceConnectivityResultDto,
 } from './source-management.api';
+import { buildMirrorCommands, getAdvisoryVexNavigationExtras } from './advisory-vex-route-helpers';
 
 const CATEGORY_ORDER = [
   'Primary',
@@ -83,8 +84,8 @@ interface CategoryGroup {
                   [class]="'mirror-mode-badge mirror-mode-badge--' + mirrorConfig()!.mode.toLowerCase()">
               {{ mirrorConfig()!.mode }}
             </span>
-            <a class="mirror-link" routerLink="mirror">Configure Mirror</a>
-            <a class="mirror-link mirror-link--connect" routerLink="mirror/client-setup">Connect to Mirror</a>
+            <a class="mirror-link" [routerLink]="mirrorDashboardLink()" queryParamsHandling="preserve">Configure Mirror</a>
+            <a class="mirror-link mirror-link--connect" [routerLink]="mirrorClientSetupLink()" queryParamsHandling="preserve">Connect to Mirror</a>
           </div>
           <div class="mirror-context-right">
             @if (isConsumerMode()) {
@@ -1053,7 +1054,15 @@ export class AdvisorySourceCatalogComponent implements OnInit {
   }
 
   onCreateMirrorDomain(): void {
-    this.router.navigate(['/integrations', 'advisory-vex-sources', 'mirror', 'new']);
+    this.router.navigate(buildMirrorCommands(this.router, 'new'), getAdvisoryVexNavigationExtras());
+  }
+
+  mirrorDashboardLink(): string[] {
+    return buildMirrorCommands(this.router);
+  }
+
+  mirrorClientSetupLink(): string[] {
+    return buildMirrorCommands(this.router, 'client-setup');
   }
 
   toggleExpanded(sourceId: string): void {
@@ -1124,19 +1133,65 @@ export class AdvisorySourceCatalogComponent implements OnInit {
 
   onCheckAll(): void {
     const items = this.catalog();
-    this.checking.set(true);
-    this.checkProgress.set({ done: 0, total: items.length });
+    const enabledIds = items
+      .filter((item) => this.isSourceEnabled(item.id))
+      .map((item) => item.id);
 
-    this.api.checkAll().pipe(take(1)).subscribe({
-      next: () => {
+    if (enabledIds.length === 0) {
+      return;
+    }
+
+    this.checking.set(true);
+    this.checkProgress.set({ done: 0, total: enabledIds.length });
+
+    // Check sources individually in parallel batches of 6 to avoid gateway timeout.
+    // The batch /check endpoint times out at 30s when checking 40+ sources.
+    const batchSize = 6;
+    let completed = 0;
+
+    const checkNext = (startIndex: number): void => {
+      const batch = enabledIds.slice(startIndex, startIndex + batchSize);
+      if (batch.length === 0) {
         this.checking.set(false);
         this.reloadStatus();
-      },
-      error: () => {
-        this.checking.set(false);
-        this.reloadStatus();
-      },
-    });
+        return;
+      }
+
+      let batchDone = 0;
+      for (const sourceId of batch) {
+        this.api.checkSource(sourceId).pipe(take(1)).subscribe({
+          next: (result) => {
+            this.statuses.update((current) => {
+              const next = new Map(current);
+              const existing = next.get(sourceId);
+              if (existing) {
+                next.set(sourceId, { ...existing, lastCheck: result });
+              } else {
+                next.set(sourceId, { sourceId, enabled: true, lastCheck: result });
+              }
+              return next;
+            });
+
+            completed++;
+            batchDone++;
+            this.checkProgress.set({ done: completed, total: enabledIds.length });
+            if (batchDone === batch.length) {
+              checkNext(startIndex + batchSize);
+            }
+          },
+          error: () => {
+            completed++;
+            batchDone++;
+            this.checkProgress.set({ done: completed, total: enabledIds.length });
+            if (batchDone === batch.length) {
+              checkNext(startIndex + batchSize);
+            }
+          },
+        });
+      }
+    };
+
+    checkNext(0);
   }
 
   onCheckSource(sourceId: string): void {