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>

tests/hermes_cli/test_models.py

@@ -101,7 +101,14 @@ class TestDetectProviderForModel:
         assert result[0] == "openrouter"
         assert result[1] == "anthropic/claude-opus-4.6"
 
-    def test_bare_name_gets_openrouter_slug(self):
+    def test_bare_name_gets_openrouter_slug(self, monkeypatch):
+        for env_var in (
+            "ANTHROPIC_API_KEY",
+            "ANTHROPIC_TOKEN",
+            "CLAUDE_CODE_TOKEN",
+            "CLAUDE_CODE_OAUTH_TOKEN",
+        ):
+            monkeypatch.delenv(env_var, raising=False)
         """Bare model names should get mapped to full OpenRouter slugs."""
         result = detect_provider_for_model("claude-opus-4.6", "openai-codex")
         assert result is not None