fix(path): add ERR_INVALID_ARG_TYPE code to path polyfill errors

[atharvasingh7007]

Summary

Fixes #28 (partially - path module only)

Upstream Node.js errors from built-in modules carry a .code property (e.g., ERR_INVALID_ARG_TYPE). The path module polyfill (backed by path-browserify) throws plain TypeError without this code property, causing conformance test failures.

This PR adds a custom path polyfill wrapper that intercepts TypeError exceptions from path-browserify and attaches the missing error.code = "ERR_INVALID_ARG_TYPE" before re-throwing.

Changes

• New: packages/nodejs/src/polyfills/path.js - Custom path polyfill wrapper (follows the same pattern as the existing crypto.js custom polyfill)
• Modified: packages/nodejs/src/polyfills.ts - Registered the custom path polyfill + added secure_exec_path_browserify esbuild alias

How it works

1. Imports the original path-browserify via a build-time alias (secure_exec_path_browserify)
2. Wraps every exported function in a try/catch
3. When a TypeError is caught without a .code property, attaches err.code = "ERR_INVALID_ARG_TYPE"
4. Also wraps path.posix.* functions for consistency

Testing

• Build passes (pnpm build)
• Type checks pass (pnpm check-types)
• Manual verification confirms all path functions (join, resolve, normalize, basename, dirname, extname, relative) now throw errors with the correct .code property

Scope

This PR addresses Issue #28 for the path module only. The remaining affected modules (assert, buffer, url, querystring, util, fs) can be handled in follow-up PRs using the same wrapper pattern.