Update: Clean up unused LLM providers (OpenRouter, Groq, Gemini) in client

backend/agent/llm_client.py

@@ -37,53 +37,6 @@ PROVIDER_CONFIG = {
             "nvidia/nemotron-3-ultra-550b-a55b",
         ],
     },
-    "openrouter": {
-        "base_url": "https://openrouter.ai/api/v1",
-        "api_key": "OPENROUTER_API_KEY",
-        "models": [
-            "moonshotai/kimi-k2.6",
-            "tencent/hy3-preview:free",
-            "inclusionai/ling-2.6-1t:free",
-            "inclusionai/ling-2.6-flash:free",
-            "google/gemma-4-26b-a4b-it:free",
-            "google/gemma-4-31b-it:free",
-            "nvidia/nemotron-3-super-120b-a12b:free",
-            "minimax/minimax-m2.5:free",
-            "liquid/lfm-2.5-1.2b-instruct:free",
-            "liquid/lfm-2.5-1.2b-thinking:free",
-            "nvidia/nemotron-3-nano-30b-a3b:free",
-            "nvidia/nemotron-nano-12b-v2-vl:free",
-            "qwen/qwen3-next-80b-a3b-instruct:free",
-            "openai/gpt-oss-120b:free",
-            "nvidia/nemotron-nano-9b-v2:free",
-            "openai/gpt-oss-20b:free",
-            "z-ai/glm-4.5-air:free",
-            "qwen/qwen3-coder:free",
-        ],
-    },
-    "groq": {
-        "base_url": "https://api.groq.com/openai/v1",
-        "api_key": "GROQ_API_KEY",
-        "models": [
-            "llama-3.1-8b-instant",
-            "llama-3.3-70b-versatile",
-            "openai/gpt-oss-120b",
-            "openai/gpt-oss-20b",
-        ],
-    },
-    "gemini": {
-        "base_url": "https://generativelanguage.googleapis.com/v1beta/openai/",
-        "api_key": "GEMINI_API_KEY",
-        "models": [
-            "gemini-3-flash-preview",
-            "gemini-3.1-flash-lite-preview",
-            "gemini-2.5-pro",
-            "gemini-2.5-flash",
-            "gemini-2.5-flash-lite",
-            "gemma-4-31b-it",
-            "gemma-4-26b-a4b-it",
-        ],
-    },
     "zai": {
         "base_url": "https://api.z.ai/api/paas/v4/",
         "api_key": "ZAI_API_KEY",