fix(bird_x): pass .env credentials to Node subprocesses for WSL2/headless auth

* chore: fix YAML error in argument-hint

* add codex auth support to responses API

* Use gpt-5.1-codex-mini as default model for Codex auth

Add CODEX_FALLBACK_MODELS chain (gpt-5.1-codex-mini → gpt-5.2) for
Codex endpoint which doesn't support standard OpenAI models like
gpt-4o-mini. Adds model fallback retry on 400 errors in the Codex
search path. Also adds test_codex_auth.py with 22 unit tests covering
JWT decoding, auth resolution, SSE parsing, and payload building.

* Pass .env credentials to Bird Node subprocesses for X auth

On platforms without browser cookie access (e.g. WSL2), Bird's
vendored Node.js module cannot read AUTH_TOKEN/CT0 from Firefox
or Chrome cookie stores. The .env config file already supports
these values, but they were only loaded into the Python config
dict — never exported to the environment of Node subprocesses.

- Add AUTH_TOKEN/CT0 to env.py config key loading
- Add set_credentials()/\_subprocess_env() to bird_x.py to inject
  credentials into the env dict passed to subprocess.run/Popen
- Call set_credentials() in main() before Bird auth detection

---------

Co-authored-by: Justin Williams <jblwilliams@gmail.com>

SKILL.md

@@ -146,6 +146,8 @@ Generated: {date} | Sources: Reddit, X, YouTube, HN, Polymarket, Web
 
 **CRITICAL: Run this command in the FOREGROUND with a 5-minute timeout. Do NOT use run_in_background. The full output contains Reddit, X, AND YouTube data that you need to read completely.**
 
+**IMPORTANT: The script handles API key/Codex auth detection automatically.** Run it and check the output to determine mode.
+
 ```bash
 # Find skill root — works in repo checkout, Claude Code, or Codex install
 for dir in \