fix: resolve build errors in pass_mgr, pcexec, and safe-restart

- Fix Go syntax error: use BoolVar for --username flag instead of string
- Fix TypeScript type errors: filter undefined values from process.env
- Fix TypeScript type error: add type assertion for fetch response
- Add .gitignore to exclude node_modules and build outputs

.gitignore

@@ -0,0 +1,30 @@
+# Dependencies
+node_modules/
+*.log
+
+# Build outputs
+dist/
+*.exe
+*.dll
+*.so
+*.dylib
+
+# Environment
+.env
+.env.local
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Go
+*.o
+*.a
+*.test
+vendor/