Full-width layout, page-shell template, httpResource async states, README

- Fix full-bleed header/footer (align-items:stretch + block hosts; centered
  content column via shared --app-content-max).
- New templates/page-shell (back-link + heading + intro + content, narrow mode);
  all pages refactored to compose it.
- Async state management with native httpResource + <app-async> wrapper that
  renders exactly one of loading/empty/error/loaded (impossible states
  unrepresentable); delayed spinner + skeleton atoms for slow/fast connections.
- Scenario interceptor (?scenario=slow|loading|empty|error) to demo every state.
- Storybook: spinner/skeleton/page-shell/async-states stories.
- README rewritten as a guide (atomic design, reuse benefits, state handling).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

angular.json

@@ -2,7 +2,8 @@
   "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
   "version": 1,
   "cli": {
-    "packageManager": "npm"
+    "packageManager": "npm",
+    "analytics": false
   },
   "newProjectRoot": "projects",
   "projects": {