fix(server): realtime loading (#14959)

#### PR Dependency Tree


* **PR #14959** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

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## Summary by CodeRabbit

* **Refactor**
* Rewired realtime and copilot services to require their runtime
dependencies, improving reliability and removing nullable/optional
runtime paths.

* **Tests**
* Centralized service creation in tests with helper factories and added
checks ensuring realtime dependency injection is configured as expected.

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packages/backend/server/src/app.module.ts

@@ -185,7 +185,10 @@ export function buildAppModule(env: Env) {
     .useIf(
       () => env.flavors.sync || env.flavors.front,
       SyncModule,
-      TelemetryModule,
+      TelemetryModule
+    )
+    .useIf(
+      () => !env.flavors.graphql && (env.flavors.sync || env.flavors.front),
       CopilotRealtimeModule
     )
     // graphql server only