fix: repair OpenCode model routing and selection (#4508)

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.

Co-authored-by: SaM13997 <139419381+SaM13997@users.noreply.github.com>

hermes_cli/model_switch.py

@@ -26,6 +26,7 @@ class ModelSwitchResult:
     provider_changed: bool = False
     api_key: str = ""
     base_url: str = ""
+    api_mode: str = ""
     persist: bool = False
     error_message: str = ""
     warning_message: str = ""
@@ -73,6 +74,7 @@ def switch_model(
         detect_provider_for_model,
         validate_requested_model,
         _PROVIDER_LABELS,
+        opencode_model_api_mode,
     )
     from hermes_cli.runtime_provider import resolve_runtime_provider
 
@@ -98,11 +100,13 @@ def switch_model(
     # Step 4: Resolve credentials for target provider
     api_key = current_api_key
     base_url = current_base_url
+    api_mode = ""
     if provider_changed:
         try:
             runtime = resolve_runtime_provider(requested=target_provider)
             api_key = runtime.get("api_key", "")
             base_url = runtime.get("base_url", "")
+            api_mode = runtime.get("api_mode", "")
         except Exception as e:
             provider_label = _PROVIDER_LABELS.get(target_provider, target_provider)
             if target_provider == "custom":
@@ -130,6 +134,7 @@ def switch_model(
             runtime = resolve_runtime_provider(requested=current_provider)
             api_key = runtime.get("api_key", "")
             base_url = runtime.get("base_url", "")
+            api_mode = runtime.get("api_mode", "")
         except Exception:
             pass
 
@@ -166,6 +171,12 @@ def switch_model(
         and ("localhost" in (base_url or "") or "127.0.0.1" in (base_url or ""))
     )
 
+    if target_provider in {"opencode-zen", "opencode-go"}:
+        # Recompute against the requested new model, not the currently-configured
+        # model used during runtime resolution. OpenCode mixes API surfaces by
+        # model family, so a same-provider model switch can change api_mode.
+        api_mode = opencode_model_api_mode(target_provider, new_model)
+
     return ModelSwitchResult(
         success=True,
         new_model=new_model,
@@ -173,6 +184,7 @@ def switch_model(
         provider_changed=provider_changed,
         api_key=api_key,
         base_url=base_url,
+        api_mode=api_mode,
         persist=bool(validation.get("persist")),
         warning_message=validation.get("message") or "",
         is_custom_target=is_custom_target,