refactor(rules): split angular.md into index + references

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

shared/rules/angular/index.md

@@ -0,0 +1,38 @@
+# Angular Code Guidelines
+
+* Use modern Angular patterns and current framework conventions.
+* Prefer standalone components, directives and pipes for new code.
+* Avoid introducing `NgModule` unless the existing project architecture requires it.
+* Keep components small and focused.
+* Keep templates simple.
+* Move complex logic out of templates.
+* Keep business logic out of components where practical.
+* Prefer services, facades or dedicated domain logic for non-trivial behavior.
+* Avoid god components and god services.
+* Keep dependencies explicit.
+* Prefer composition over inheritance.
+* Avoid unnecessary abstractions.
+* Avoid unnecessary wrapper components.
+* Follow the existing project architecture unless there is a strong reason to change it.
+
+## Safety Rule
+
+* Angular frontend code is never a security boundary.
+* Client-side validation, guards, hidden controls and disabled UI elements do not replace backend enforcement.
+* Do not bypass Angular's built-in security mechanisms without a verified and explicit reason.
+* Prefer safe framework defaults over custom low-level behavior.
+
+## Detailed guidance
+
+Read the matching reference file before working in that area:
+
+| Read this reference for... | ...this kind of work |
+| --- | --- |
+| `references/components-and-state.md` | Component structure, signal-based state |
+| `references/templates-and-styling.md` | Template markup, CSS/styling |
+| `references/rxjs.md` | RxJS observables and subscriptions |
+| `references/services-and-http.md` | Dependency injection, services, HTTP/API access |
+| `references/forms-and-routing.md` | Reactive forms, routing |
+| `references/security-and-accessibility.md` | Security, DOM/browser APIs, accessibility |
+| `references/performance.md` | Performance work and its priority order |
+| `references/testing-and-architecture.md` | Testing, architecture, code quality, dependency rules |