fix(auth): align Codex OAuth persistence paths (#37517)

* fix(desktop): codex OAuth onboarding now resolves on fresh install

The desktop codex device-code worker persisted tokens with a hand-rolled
pool.add_entry(), writing only credential_pool.openai-codex. It never set
active_provider, so on a fresh install the onboarding setup.runtime_check
resolved provider "auto", couldn't detect the Codex OAuth session, and raised
"No inference provider configured" — while setup.status (which sniffs the pool)
reported configured. The disagreement surfaced as the onboarding banner
"Connected, but Hermes still cannot resolve a usable provider."

Use the canonical _save_codex_tokens() instead, matching the CLI's
`hermes auth add openai-codex` path and the Nous/MiniMax dashboard workers.
It writes the providers.openai-codex singleton (setting active_provider) and
syncs the pool.

* fix(auth): align Codex OAuth persistence paths

Ensure desktop and CLI Codex OAuth logins both write the canonical provider state so fresh installs resolve a usable runtime provider.

---------

Co-authored-by: teknium1 <127238744+teknium1@users.noreply.github.com>

agent/credential_pool.py

@@ -1891,6 +1891,7 @@ def _seed_from_singletons(provider: str, entries: List[PooledCredential]) -> Tup
         # via `hermes auth openai-codex`.
         if isinstance(tokens, dict) and tokens.get("access_token"):
             active_sources.add("device_code")
+            custom_label = str(state.get("label") or "").strip()
             changed |= _upsert_entry(
                 entries,
                 provider,
@@ -1902,7 +1903,7 @@ def _seed_from_singletons(provider: str, entries: List[PooledCredential]) -> Tup
                     "refresh_token": tokens.get("refresh_token"),
                     "base_url": "https://chatgpt.com/backend-api/codex",
                     "last_refresh": state.get("last_refresh"),
-                    "label": label_from_token(tokens.get("access_token", ""), "device_code"),
+                    "label": custom_label or label_from_token(tokens.get("access_token", ""), "device_code"),
                 },
             )