refactor(openclaw): Phase 24 B4 — 封存舊 fallback Provider 方法

[ARCHIVED] _call_ollama / _call_gemini / _call_claude
- 這三個方法為 USE_AI_ROUTER=false 回滾保留路徑
- 新路徑: USE_AI_ROUTER=true → AIRouterExecutor (ai_router.py)
- 新 Provider: ai_providers/ollama.py / gemini.py / claude.py
- 封存而非刪除: 完整移除等 Phase 24 全驗收後 (ADR-052 D11)

R3 觀察結果 (通過 ✅):
- openclaw_nemo provider: 12/12 incidents 全部正確路由
- 信心度: 0.8~0.9 正常
- USE_AI_ROUTER=true 生效確認

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/services/openclaw.py

@@ -343,7 +343,13 @@ class OpenClawService:
             )
             return None
 
-    # AI Provider Implementations - Enhanced with Structured Output
+    # =========================================================================
+    # [ARCHIVED Phase 24 B4 — 2026-04-03 ogt]
+    # 以下三個方法 (_call_ollama/_call_gemini/_call_claude) 為舊版 fallback chain
+    # 新路徑: USE_AI_ROUTER=true → _call_with_fallback → AIRouterExecutor (ai_router.py)
+    # 新 Provider 實作: apps/api/src/services/ai_providers/ (OllamaProvider/GeminiProvider/ClaudeProvider)
+    # 回滾保留: USE_AI_ROUTER=false 時仍由 _call_with_fallback (line ~993) 呼叫此區塊
+    # 完整移除時機: Phase 24 完整驗收後 (ADR-052 D11)
     # =========================================================================
 
     async def _call_ollama(self, prompt: str) -> tuple[str, bool]:
@@ -549,8 +555,12 @@ class OpenClawService:
             logger.warning("claude_call_failed", error=str(e))
             return str(e), False
 
-    # 2026-03-29 ogt: _call_nvidia 已移至 nvidia_provider.py
-    # 符合模組化規範 - 所有 NVIDIA API 呼叫統一由 NvidiaProvider 處理
+    # 2026-03-29 ogt: _call_nvidia 已移至 nvidia_provider.py (ARCHIVED)
+    # 符合模組化規範 - 所有 NVIDIA API 呼叫統一由 NvidiaProvider / OpenClawNemoProvider 處理
+
+    # =========================================================================
+    # [END ARCHIVED Phase 24 B4]
+    # =========================================================================
 
     # =========================================================================
     # Mock LLM - Intelligent Fallback with SignOz Data