feat(agent): wire MiniMax-M2.7 for minimax-oauth provider

Wire MiniMax-M2.7 and MiniMax-M2.7-highspeed into the model catalog,
CLI model picker, and agent auxiliary/metadata subsystems.

Changes:
- hermes_cli/models.py:
  - Add 'minimax-oauth' to _PROVIDER_MODELS with MiniMax-M2.7 and
    MiniMax-M2.7-highspeed
  - Add ProviderEntry('minimax-oauth', 'MiniMax (OAuth)', ...) to
    CANONICAL_PROVIDERS near existing minimax entries
  - Add aliases: minimax-portal, minimax-global, minimax_oauth in
    _PROVIDER_ALIASES
- hermes_cli/main.py:
  - Add 'minimax-oauth' to provider_labels dict
  - Insert 'minimax-oauth' into providers list in
    select_provider_and_model() near the other minimax entries
  - Add 'minimax-oauth' to --provider argparse choices
  - Add _model_flow_minimax_oauth() function: ensures login via
    _login_minimax_oauth(), resolves runtime credentials, prompts for
    model selection, saves model choice and config
  - Add dispatch elif branch for selected_provider == 'minimax-oauth'
- agent/auxiliary_client.py:
  - Add 'minimax-oauth': 'MiniMax-M2.7-highspeed' to
    _API_KEY_PROVIDER_AUX_MODELS
  - Add 'minimax-oauth' to _ANTHROPIC_COMPAT_PROVIDERS set
- agent/model_metadata.py:
  - Add 'minimax-oauth' to _PROVIDER_PREFIXES frozenset
  - MiniMax-M2.7 context length (200_000) already covered by the
    existing 'minimax' substring match in DEFAULT_CONTEXT_LENGTHS

hermes_cli/main.py

@@ -1770,6 +1770,8 @@ def select_provider_and_model(args=None):
         _model_flow_openai_codex(config, current_model)
     elif selected_provider == "qwen-oauth":
         _model_flow_qwen_oauth(config, current_model)
+    elif selected_provider == "minimax-oauth":
+        _model_flow_minimax_oauth(config, current_model, args=args)
     elif selected_provider == "google-gemini-cli":
         _model_flow_google_gemini_cli(config, current_model)
     elif selected_provider == "copilot-acp":
@@ -2658,6 +2660,53 @@ def _model_flow_qwen_oauth(_config, current_model=""):
         print("No change.")
 
 
+def _model_flow_minimax_oauth(config, current_model="", args=None):
+    """MiniMax OAuth provider: ensure logged in, then pick model."""
+    from hermes_cli.auth import (
+        get_provider_auth_state,
+        _prompt_model_selection,
+        _save_model_choice,
+        _update_config_for_provider,
+        resolve_minimax_oauth_runtime_credentials,
+        AuthError,
+        format_auth_error,
+        _login_minimax_oauth,
+        PROVIDER_REGISTRY,
+    )
+    state = get_provider_auth_state("minimax-oauth")
+    if not state or not state.get("access_token"):
+        print("Not logged into MiniMax. Starting OAuth login...")
+        print()
+        try:
+            mock_args = argparse.Namespace(
+                region=getattr(args, "region", None) or "global",
+                no_browser=bool(getattr(args, "no_browser", False)),
+                timeout=getattr(args, "timeout", None) or 15.0,
+            )
+            _login_minimax_oauth(mock_args, PROVIDER_REGISTRY["minimax-oauth"])
+        except SystemExit:
+            print("Login cancelled or failed.")
+            return
+        except Exception as exc:
+            print(f"Login failed: {exc}")
+            return
+
+    try:
+        creds = resolve_minimax_oauth_runtime_credentials()
+    except AuthError as exc:
+        print(format_auth_error(exc))
+        return
+
+    from hermes_cli.models import _PROVIDER_MODELS
+    model_ids = _PROVIDER_MODELS.get("minimax-oauth", [])
+    selected = _prompt_model_selection(model_ids, current_model)
+    if not selected:
+        return
+    _save_model_choice(selected)
+    _update_config_for_provider("minimax-oauth", creds["base_url"])
+    print(f"\u2713 Using MiniMax model: {selected}")
+
+
 def _model_flow_google_gemini_cli(_config, current_model=""):
     """Google Gemini OAuth (PKCE) via Cloud Code Assist — supports free AND paid tiers.