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>

scripts/lib/bird_x.py

@@ -24,6 +24,24 @@ DEPTH_CONFIG = {
     "deep": 60,
 }
 
+# Module-level credentials injected from .env config
+_credentials: Dict[str, str] = {}
+
+
+def set_credentials(auth_token: Optional[str], ct0: Optional[str]):
+    """Inject AUTH_TOKEN/CT0 from .env config so Node subprocesses can use them."""
+    if auth_token:
+        _credentials['AUTH_TOKEN'] = auth_token
+    if ct0:
+        _credentials['CT0'] = ct0
+
+
+def _subprocess_env() -> Dict[str, str]:
+    """Build env dict for Node subprocesses, merging injected credentials."""
+    env = os.environ.copy()
+    env.update(_credentials)
+    return env
+
 
 def _log(msg: str):
     """Log to stderr."""
@@ -112,6 +130,7 @@ def is_bird_authenticated() -> Optional[str]:
             capture_output=True,
             text=True,
             timeout=15,
+            env=_subprocess_env(),
         )
         if result.returncode == 0 and result.stdout.strip():
             return result.stdout.strip().split('\n')[0]
@@ -187,6 +206,7 @@ def _run_bird_search(query: str, count: int, timeout: int) -> Dict[str, Any]:
             stderr=subprocess.PIPE,
             text=True,
             preexec_fn=preexec,
+            env=_subprocess_env(),
         )
 
         # Register for cleanup tracking (if available)