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

agent/auxiliary_client.py

@@ -210,6 +210,7 @@ _API_KEY_PROVIDER_AUX_MODELS: Dict[str, str] = {
     "kimi-coding-cn": "kimi-k2-turbo-preview",
     "gmi": "google/gemini-3.1-flash-lite-preview",
     "minimax": "MiniMax-M2.7",
+    "minimax-oauth": "MiniMax-M2.7-highspeed",
     "minimax-cn": "MiniMax-M2.7",
     "anthropic": "claude-haiku-4-5-20251001",
     "ai-gateway": "google/gemini-3-flash",
@@ -3043,7 +3044,7 @@ def _get_task_extra_body(task: str) -> Dict[str, Any]:
 
 # Providers that use Anthropic-compatible endpoints (via OpenAI SDK wrapper).
 # Their image content blocks must use Anthropic format, not OpenAI format.
-_ANTHROPIC_COMPAT_PROVIDERS = frozenset({"minimax", "minimax-cn"})
+_ANTHROPIC_COMPAT_PROVIDERS = frozenset({"minimax", "minimax-oauth", "minimax-cn"})
 
 
 def _is_anthropic_compat_endpoint(provider: str, base_url: str) -> bool:

agent/model_metadata.py

@@ -46,7 +46,7 @@ def _resolve_requests_verify() -> bool | str:
 # are preserved so the full model name reaches cache lookups and server queries.
 _PROVIDER_PREFIXES: frozenset[str] = frozenset({
     "openrouter", "nous", "openai-codex", "copilot", "copilot-acp",
-    "gemini", "ollama-cloud", "zai", "kimi-coding", "kimi-coding-cn", "stepfun", "minimax", "minimax-cn", "anthropic", "deepseek",
+    "gemini", "ollama-cloud", "zai", "kimi-coding", "kimi-coding-cn", "stepfun", "minimax", "minimax-oauth", "minimax-cn", "anthropic", "deepseek",
     "opencode-zen", "opencode-go", "ai-gateway", "kilocode", "alibaba",
     "qwen-oauth",
     "xiaomi",