fix: address second PR review — clean replace, IDE failure bubbling, bun validation

- cpSync now does rmSync before copy to avoid stale file merges
- setupIDEs() returns failed IDE list; install reports partial success
- runSmartInstall() returns boolean status instead of void
- Worker port in next-steps URL reads CLAUDE_MEM_WORKER_PORT env var
- Goose YAML regex stops at column-0 keys (prevents eating sibling sections)
- AGENTS.md uninstall removes header-only stub files
- findBunPath() validated before use in WindsurfHooksInstaller
- Cursor marked unsupported in ide-detection until installer is wired

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/services/integrations/WindsurfHooksInstaller.ts

@@ -278,6 +278,11 @@ export async function installWindsurfHooks(): Promise<number> {
 
   // Find bun executable — required because worker-service.cjs uses bun:sqlite
   const bunPath = findBunPath();
+  if (!bunPath) {
+    console.error('Could not find Bun runtime');
+    console.error('   Install Bun: curl -fsSL https://bun.sh/install | bash');
+    return 1;
+  }
 
   // IMPORTANT: Tilde expansion is NOT supported in working_directory — use absolute paths
   const workingDirectory = path.dirname(workerServicePath);