docs: add mpv.launchMode to config docs, add changelog:docs generator, format

- Document the new mpv.launchMode option in the configuration docs page
- Add changelog:docs command to auto-generate docs-site/changelog.md from root CHANGELOG.md
- Add breaking changes support to the changelog fragment generator
- Fix docs-sync test to only compare current minor release headings
- Apply prettier formatting to source files

src/config/config.test.ts

@@ -2125,10 +2125,7 @@ test('template generator includes known keys', () => {
     /"dpadFallback": "horizontal",? \/\/ Optional D-pad fallback used when this analog controller action should also read D-pad input\. Values: none \| horizontal \| vertical/,
   );
   assert.match(output, /"port": 6678,? \/\/ Annotated subtitle websocket server port\./);
-  assert.match(
-    output,
-    /"openBrowser": false,? \/\/ Open browser setting\. Values: true \| false/,
-  );
+  assert.match(output, /"openBrowser": false,? \/\/ Open browser setting\. Values: true \| false/);
   assert.match(
     output,
     /"enabled": false,? \/\/ Enable overlay controller support through the Chrome Gamepad API\. Values: true \| false/,