feat(provider): add OpenCode Zen and OpenCode Go providers

Add support for OpenCode Zen (pay-as-you-go, 35+ curated models) and
OpenCode Go ($10/month subscription, open models) as first-class providers.

Both are OpenAI-compatible endpoints resolved via the generic api_key
provider flow — no custom adapter needed.

Files changed:
- hermes_cli/auth.py — ProviderConfig entries + aliases
- hermes_cli/config.py — OPENCODE_ZEN/GO API key env vars
- hermes_cli/models.py — model catalogs, labels, aliases, provider order
- hermes_cli/main.py — provider labels, menu entries, model flow dispatch
- hermes_cli/setup.py — setup wizard branches (idx 10, 11)
- agent/model_metadata.py — context lengths for all OpenCode models
- agent/auxiliary_client.py — default aux models
- .env.example — documentation

Co-authored-by: DevAgarwal2 <DevAgarwal2@users.noreply.github.com>

agent/auxiliary_client.py

@@ -58,6 +58,8 @@ _API_KEY_PROVIDER_AUX_MODELS: Dict[str, str] = {
     "minimax-cn": "MiniMax-M2.5-highspeed",
     "anthropic": "claude-haiku-4-5-20251001",
     "ai-gateway": "google/gemini-3-flash",
+    "opencode-zen": "gemini-3-flash",
+    "opencode-go": "glm-5",
 }
 
 # OpenRouter app attribution headers