Fix topology layout API call to not pass context filters by default

The PlatformContextStore pre-selects regions/environments which caused
the layout API to return 400. The topology page should show everything
on initial load - filtering is done client-side via the filter bar.

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

src/Web/StellaOps.Web/src/app/features/topology/topology-graph-page.component.ts

@@ -10,7 +10,6 @@ import { FormsModule } from '@angular/forms';
 import { RouterLink } from '@angular/router';
 import { catchError, of, take } from 'rxjs';
 
-import { PlatformContextStore } from '../../core/context/platform-context.store';
 import { TopologyLayoutService } from './topology-layout.service';
 import { TopologyGraphComponent } from './topology-graph.component';
 import {
@@ -444,7 +443,6 @@ import {
 })
 export class TopologyGraphPageComponent {
   private readonly layoutService = inject(TopologyLayoutService);
-  readonly context = inject(PlatformContextStore);
 
   readonly loading = signal(false);
   readonly error = signal<string | null>(null);
@@ -479,7 +477,7 @@ export class TopologyGraphPageComponent {
     const matchedRegionIds = new Set<string>();
 
     const filteredNodes = data.nodes.filter((n) => {
-      if (n.kind === 'region') return true; // keep all regions initially
+      if (n.kind === 'region') return true;
 
       const matchesSearch = !query
         || n.label.toLowerCase().includes(query)
@@ -507,12 +505,7 @@ export class TopologyGraphPageComponent {
   });
 
   constructor() {
-    this.context.initialize();
-
-    effect(() => {
-      this.context.contextVersion();
-      this.load();
-    });
+    this.load();
   }
 
   onNodeSelected(node: TopologyPositionedNode): void {
@@ -535,7 +528,7 @@ export class TopologyGraphPageComponent {
     this.error.set(null);
 
     this.layoutService
-      .getLayout(this.context)
+      .getLayout()
       .pipe(
         take(1),
         catchError((err: unknown) => {

src/Web/StellaOps.Web/src/app/features/topology/topology-layout.service.ts

@@ -2,30 +2,25 @@ import { HttpClient, HttpParams } from '@angular/common/http';
 import { Injectable, inject } from '@angular/core';
 import { Observable } from 'rxjs';
 
-import { PlatformContextStore } from '../../core/context/platform-context.store';
 import { TopologyLayoutResponse } from './topology-layout.models';
 
 @Injectable({ providedIn: 'root' })
 export class TopologyLayoutService {
   private readonly http = inject(HttpClient);
 
-  getLayout(
-    context: PlatformContextStore,
-    options?: {
-      direction?: 'left-to-right' | 'top-to-bottom';
-      effort?: 'draft' | 'balanced' | 'best';
-    },
-  ): Observable<TopologyLayoutResponse> {
+  getLayout(options?: {
+    region?: string;
+    environment?: string;
+    direction?: 'left-to-right' | 'top-to-bottom';
+    effort?: 'draft' | 'balanced' | 'best';
+  }): Observable<TopologyLayoutResponse> {
     let params = new HttpParams();
 
-    const regions = context.selectedRegions();
-    const environments = context.selectedEnvironments();
-
-    if (regions.length > 0) {
-      params = params.set('region', regions.join(','));
+    if (options?.region) {
+      params = params.set('region', options.region);
     }
-    if (environments.length > 0) {
-      params = params.set('environment', environments.join(','));
+    if (options?.environment) {
+      params = params.set('environment', options.environment);
     }
     if (options?.direction) {
       params = params.set('direction', options.direction);