fix: keep SSR resource watchers for cache invalidation

The fs.watch callback serves dual purpose: (1) invalidating
resourceCache on file change, and (2) sending HMR WebSocket events.
The HMR part is already independently gated by componentIds, which
are only populated for client transforms. Skipping watcher
registration for SSR would leave resourceCache stale when external
templates/styles change.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Brooooooklyn

napi/angular-compiler/vite-plugin/index.ts

@@ -472,10 +472,14 @@ export function angular(options: PluginOptions = {}): Plugin[] {
           // bundles (see @angular/build application-code-bundle.js).
           const isSSR = !!options?.ssr
 
-          // Track dependencies for HMR (client-side only)
+          // Track dependencies for resource cache invalidation and HMR.
           // DON'T use addWatchFile - it creates modules in Vite's graph!
           // Instead, use our custom watcher that doesn't create modules.
-          if (watchMode && viteServer && !isSSR) {
+          // Note: watchers are registered for both client AND SSR transforms
+          // because the fs.watch callback invalidates resourceCache (needed by
+          // both). The HMR-specific behavior inside the callback is separately
+          // gated by componentIds, which are only populated for client transforms.
+          if (watchMode && viteServer) {
             const watchFn = (viteServer as any).__angularWatchTemplate
             for (const dep of dependencies) {
               const normalizedDep = normalizePath(dep)