test: migrate from Karma and Jasmine to Vitest

Karma is deprecated and depends on braces, which has no patched release for GHSA-vfj7-8cjw-p6xm. Tests now run through the @angular/build unit-test builder with Vitest and jsdom. fakeAsync is replaced by Vitest fake timers, and zone.js is dropped because the zoneless app only loaded it for the Karma test polyfills.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tsconfig.spec.json

@@ -2,7 +2,7 @@
   "extends": "./tsconfig.json",
   "compilerOptions": {
     "outDir": "./dist/out-tsc/spec",
-    "types": ["jasmine", "node"]
+    "types": ["vitest/globals", "node"]
   },
   "include": ["src/**/*.spec.ts", "src/**/*.d.ts"]
 }