chore: 添加 GPT-5.4 模型定义

opencode.jsonc

@@ -43,6 +43,12 @@
         "apiKey": "{env:LITELLM_API_KEY}"
       },
       "models": {
+        "gpt-5.4": {
+          "name": "GPT-5.4",
+          "reasoning": true,
+          "modalities": { "input": ["text", "image"], "output": ["text"] },
+          "limit": { "context": 1050000, "input": 272000, "output": 128000 }
+        },
         "gpt-5.2": {
           "name": "GPT-5.2",
           "reasoning": true,