config: enable all 5 models in default config

Updated default_config.json to enable all trading models:
- claude-sonnet-4-5
- deepseek-chat-v3.1
- qwen3-max
- gemini-2.5-flash
- gpt-5

This ensures that when models=[] is passed to the API, all 5 models
will run instead of just gpt-5.

configs/default_config.json

@@ -6,30 +6,28 @@
   },
   "models": [
     {
-      "name": "claude-3.7-sonnet",
+      "name": "claude-sonnet-4-5",
-      "basemodel": "anthropic/claude-3.7-sonnet", 
+      "basemodel": "anthropic/claude-sonnet-4.5",
-      "signature": "claude-3.7-sonnet",
+      "signature": "claude-sonnet-4.5",
-      "enabled": false,
+      "enabled": true
-      "openai_base_url": "Optional: YOUR_OPENAI_BASE_URL,you can write them in .env file",
-      "openai_api_key": "Optional: YOUR_OPENAI_API_KEY,you can write them in .env file" 
     },
     {
       "name": "deepseek-chat-v3.1",
       "basemodel": "deepseek/deepseek-chat-v3.1",
       "signature": "deepseek-chat-v3.1",
-      "enabled": false
+      "enabled": true
     },
     {
       "name": "qwen3-max",
       "basemodel": "qwen/qwen3-max",
       "signature": "qwen3-max",
-      "enabled": false
+      "enabled": true
     },
     {
       "name": "gemini-2.5-flash",
       "basemodel": "google/gemini-2.5-flash",
       "signature": "gemini-2.5-flash",
-      "enabled": false
+      "enabled": true
     },
     {
       "name": "gpt-5",