fix: repair OpenCode model routing and selection

OpenCode Zen and Go are mixed-API-surface providers — different models
behind them use different API surfaces (GPT on Zen uses codex_responses,
Claude on Zen uses anthropic_messages, MiniMax on Go uses
anthropic_messages, GLM/Kimi on Go use chat_completions).

Changes:
- Add normalize_opencode_model_id() and opencode_model_api_mode() to
  models.py for model ID normalization and API surface routing
- Add _provider_supports_explicit_api_mode() to runtime_provider.py
  to prevent stale api_mode from leaking across provider switches
- Wire opencode routing into all three api_mode resolution paths:
  pool entry, api_key provider, and explicit runtime
- Add api_mode field to ModelSwitchResult for propagation through the
  switch pipeline
- Consolidate _PROVIDER_MODELS from main.py into models.py (single
  source of truth, eliminates duplicate dict)
- Add opencode normalization to setup wizard and model picker flows
- Add opencode block to _normalize_model_for_provider in CLI
- Add opencode-zen/go fallback model lists to setup.py

Tests: 160 targeted tests pass (26 new tests covering normalization,
api_mode routing per provider/model, persistence, and setup wizard
normalization).

Based on PR #3017 by SaM13997.

hermes_cli/auth.py

@@ -200,6 +200,10 @@ PROVIDER_REGISTRY: Dict[str, ProviderConfig] = {
         id="opencode-go",
         name="OpenCode Go",
         auth_type="api_key",
+        # OpenCode Go mixes API surfaces by model:
+        # - GLM / Kimi use OpenAI-compatible chat completions under /v1
+        # - MiniMax models use Anthropic Messages under /v1/messages
+        # Keep the provider base at /v1 and select api_mode per-model.
         inference_base_url="https://opencode.ai/zen/go/v1",
         api_key_env_vars=("OPENCODE_GO_API_KEY",),
         base_url_env_var="OPENCODE_GO_BASE_URL",