Always enable diff highlighting in playground output viewer

[Copilot]

The newChangeDiff emitter option was meant to be opt-in for the C#/Python emitters, but a default of true made it always-on. Per the issue, the feature is generally useful — remove the config and make it unconditional.

Changes

• packages/playground: dropped the newChangeDiff field from PlaygroundEmitterOptions and the highlightChanges prop plumbing through OutputView → createFileViewer → FileViewerComponent → useFileChanges. Changed-file/line tracking now always runs.
• website/src/components/playground-component/playground.tsx: removed the newChangeDiff: true overrides on the python/csharp emitter entries.
• Changelog: added a breaking entry for @typespec/playground (option removed from the public API).

Before / after

 export interface PlaygroundEmitterOptions {
   debounce?: number;
-  /** When true, highlights changed files and lines after recompilation. */
-  newChangeDiff?: boolean;
 }

 emitterOptions={{
-  "@typespec/http-client-python": { debounce: 500, newChangeDiff: true },
-  "@typespec/http-client-csharp": { debounce: 500, newChangeDiff: true },
+  "@typespec/http-client-python": { debounce: 500 },
+  "@typespec/http-client-csharp": { debounce: 500 },
 }}

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@typespec/playground@10468

commit: 82b8f5a

[azure-sdk]

You can try these changes here

🛝 Playground	🌐 Website	🛝 VSCode Extension