fix: make Codex browse runtime work on Windows

[49EHyeon42]

Summary

• avoid eagerly resolving server.ts on Windows when the Node bundle path is used
• expose node_modules in the Codex runtime root so the Windows Node bundle can resolve runtime deps
• teach find-browse to locate browse.exe / find-browse.exe on Windows
• add regression coverage for the Windows-specific runtime and binary discovery paths

Repro

1. On Windows, run the documented global Codex install flow:
   • git clone --single-branch --depth 1 https://github.com/garrytan/gstack.git ~/gstack
   • cd ~/gstack && ./setup --host codex
2. Run ~/.codex/skills/gstack/browse/dist/browse status
3. Before this patch, the install could fail early because:
   • cli.ts resolves server.ts eagerly even on Windows
   • the Codex runtime root exposes browse/dist but not node_modules
   • find-browse only looks for browse, not browse.exe

Fix

• make SERVER_SCRIPT lazy on Windows so the Node path does not require browse/src/server.ts
• link node_modules into ~/.codex/skills/gstack so server-node.mjs can resolve playwright / diff
• prefer .exe binaries in the Windows locator / shim paths

Validation

• bun test browse/test/config.test.ts browse/test/find-browse.test.ts
• smoke-tested a minimal Codex runtime root on Windows: startup now reaches Playwright launch instead of failing on missing server.ts / server-node.mjs path resolution