feat: add claude-opus-4-5 model configuration with thinking mode

opencode.json

@@ -15,6 +15,14 @@
               "budgetTokens": 16000
             }
           }
+        },
+        "claude-opus-4-5": {
+          "options": {
+            "thinking": {
+              "type": "enabled",
+              "budgetTokens": 16000
+            }
+          }
         }
       }
     }