fix: add pre-restart delay to prevent MCP server failures on plugin updates

Add 2-second delay before worker restart in ensureWorkerVersionMatches() to
give files time to sync. Fixes issue where MCP server would fail after plugin
updates because restart happened too quickly.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/shared/hook-constants.ts

@@ -3,6 +3,7 @@ export const HOOK_TIMEOUTS = {
   HEALTH_CHECK: 1000,         // Worker health check (up from 500ms)
   WORKER_STARTUP_WAIT: 1000,
   WORKER_STARTUP_RETRIES: 15,
+  PRE_RESTART_SETTLE_DELAY: 2000,  // Give files time to sync before restart
   WINDOWS_MULTIPLIER: 1.5     // Platform-specific adjustment
 } as const;