Address PR review feedback for synchronized output

- Remove synchronizedOutputTimeout public API, hardcode 1s timeout
- Extract SynchronizedOutputHandler class for cleaner code
- Update spec URL to contour-terminal/vt-extensions
- Remove unnecessary comment in InputHandler
- Delete unit tests, add integration tests in SharedRendererTests
- Fix whitespace issue

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/common/services/OptionsService.ts

@@ -37,7 +37,6 @@ export const DEFAULT_OPTIONS: Readonly<Required<ITerminalOptions>> = {
   scrollSensitivity: 1,
   screenReaderMode: false,
   smoothScrollDuration: 0,
-  synchronizedOutputTimeout: 5000,
   macOptionIsMeta: false,
   macOptionClickForcesSelection: false,
   minimumContrastRatio: 1,

src/common/services/Services.ts

@@ -259,7 +259,6 @@ export interface ITerminalOptions {
   scrollOnUserInput?: boolean;
   scrollSensitivity?: number;
   smoothScrollDuration?: number;
-  synchronizedOutputTimeout?: number;
   tabStopWidth?: number;
   theme?: ITheme;
   windowsMode?: boolean;