feat(qwen): add Qwen OAuth provider with portal request support

Based on #6079 by @tunamitom with critical fixes and comprehensive tests.

Changes from #6079:
- Fix: sanitization overwrite bug — Qwen message prep now runs AFTER codex
  field sanitization, not before (was silently discarding Qwen transforms)
- Fix: missing try/except AuthError in runtime_provider.py — stale Qwen
  credentials now fall through to next provider on auto-detect
- Fix: 'qwen' alias conflict — bare 'qwen' stays mapped to 'alibaba'
  (DashScope); use 'qwen-portal' or 'qwen-cli' for the OAuth provider
- Fix: hardcoded ['coder-model'] replaced with live API fetch + curated
  fallback list (qwen3-coder-plus, qwen3-coder)
- Fix: extract _is_qwen_portal() helper + _qwen_portal_headers() to replace
  5 inline 'portal.qwen.ai' string checks and share headers between init
  and credential swap
- Fix: add Qwen branch to _apply_client_headers_for_base_url for mid-session
  credential swaps
- Fix: remove suspicious TypeError catch blocks around _prompt_provider_choice
- Fix: handle bare string items in content lists (were silently dropped)
- Fix: remove redundant dict() copies after deepcopy in message prep
- Revert: unrelated ai-gateway test mock removal and model_switch.py comment deletion

New tests (30 test functions):
- _qwen_cli_auth_path, _read_qwen_cli_tokens (success + 3 error paths)
- _save_qwen_cli_tokens (roundtrip, parent creation, permissions)
- _qwen_access_token_is_expiring (5 edge cases: fresh, expired, within skew,
  None, non-numeric)
- _refresh_qwen_cli_tokens (success, preserve old refresh, 4 error paths,
  default expires_in, disk persistence)
- resolve_qwen_runtime_credentials (fresh, auto-refresh, force-refresh,
  missing token, env override)
- get_qwen_auth_status (logged in, not logged in)
- Runtime provider resolution (direct, pool entry, alias)
- _build_api_kwargs (metadata, vl_high_resolution_images, message formatting,
  max_tokens suppression)

hermes_cli/runtime_provider.py

@@ -14,11 +14,13 @@ from agent.credential_pool import CredentialPool, PooledCredential, get_custom_p
 from hermes_cli.auth import (
     AuthError,
     DEFAULT_CODEX_BASE_URL,
+    DEFAULT_QWEN_BASE_URL,
     PROVIDER_REGISTRY,
     format_auth_error,
     resolve_provider,
     resolve_nous_runtime_credentials,
     resolve_codex_runtime_credentials,
+    resolve_qwen_runtime_credentials,
     resolve_api_key_provider_credentials,
     resolve_external_process_provider_credentials,
     has_usable_secret,
@@ -148,6 +150,9 @@ def _resolve_runtime_from_pool_entry(
     if provider == "openai-codex":
         api_mode = "codex_responses"
         base_url = base_url or DEFAULT_CODEX_BASE_URL
+    elif provider == "qwen-oauth":
+        api_mode = "chat_completions"
+        base_url = base_url or DEFAULT_QWEN_BASE_URL
     elif provider == "anthropic":
         api_mode = "anthropic_messages"
         cfg_provider = str(model_cfg.get("provider") or "").strip().lower()
@@ -691,6 +696,24 @@ def resolve_runtime_provider(
             logger.info("Auto-detected Codex provider but credentials failed; "
                         "falling through to next provider.")
 
+    if provider == "qwen-oauth":
+        try:
+            creds = resolve_qwen_runtime_credentials()
+            return {
+                "provider": "qwen-oauth",
+                "api_mode": "chat_completions",
+                "base_url": creds.get("base_url", "").rstrip("/"),
+                "api_key": creds.get("api_key", ""),
+                "source": creds.get("source", "qwen-cli"),
+                "expires_at_ms": creds.get("expires_at_ms"),
+                "requested_provider": requested_provider,
+            }
+        except AuthError:
+            if requested_provider != "auto":
+                raise
+            logger.info("Qwen OAuth credentials failed; "
+                        "falling through to next provider.")
+
     if provider == "copilot-acp":
         creds = resolve_external_process_provider_credentials(provider)
         return {