chore: 添加后端通信相关依赖

- 添加 eventsource-parser 依赖用于 SSE 事件解析
- 新增后端配置项（iccoder.backend.baseUrl 和 timeout）
- 更新 pnpm-lock.yaml 锁定依赖版本

package.json

@@ -91,6 +91,26 @@
           "type": "webview"
         }
       ]
+    },
+    "configuration": {
+      "title": "IC Coder",
+      "properties": {
+        "icCoder.backendUrl": {
+          "type": "string",
+          "default": "http://localhost:2233",
+          "description": "后端服务地址"
+        },
+        "icCoder.timeout": {
+          "type": "number",
+          "default": 60000,
+          "description": "请求超时时间（毫秒）"
+        },
+        "icCoder.userId": {
+          "type": "string",
+          "default": "default-user",
+          "description": "用户ID（临时配置）"
+        }
+      }
     }
   },
   "scripts": {
@@ -125,6 +145,7 @@
   ],
   "dependencies": {
     "@wavedrom/doppler": "^1.14.0",
+    "eventsource-parser": "^3.0.6",
     "iconv-lite": "^0.7.1",
     "onml": "^2.1.0",
     "style-mod": "^4.1.3",