fix(vite-plugin-angular): reject @service on Angular below 22

Addresses CodeRabbit review feedback. When a `@Service` class was
compiled against Angular <22, the version gate did a bare `break`,
leaving `targetType` at its `FactoryTarget.Injectable` default — the
unconditional factory block then emitted an `Injectable`-target `ɵfac`
with no `ɵprov`, a silently wrong half-compiled class.

`@Service` does not exist before Angular 22, so this is a broken
configuration. Set `classCompileError` instead, surfacing a clear
`@Service requires Angular 22 or later` error before factory emission
rather than degrading silently.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: brandonroberts

packages/vite-plugin-angular/src/lib/compiler/compile.ts

@@ -974,8 +974,15 @@ export function compile(
 
         case 'Service': {
           // `@Service` (and the `compileService` compiler API) landed in
-          // Angular 22. Skip on older peers where the API is absent.
-          if (!angularVersionAtLeast(22)) break;
+          // Angular 22. On older peers the decorator does not exist; fail
+          // loudly rather than falling through and emitting a default
+          // `Injectable`-target factory with no `ɵprov`.
+          if (!angularVersionAtLeast(22)) {
+            classCompileError = new Error(
+              `[fast-compile] @Service on ${className} requires Angular 22 or later`,
+            );
+            break;
+          }
           targetType = (FactoryTarget as any).Service;
           const serviceMeta: any = {
             name: className,