refactor(chat): 优化聊天界面滚动逻辑并清理欢迎页面VM代码

- 使用 scrollToPositionWithOffset 替代复杂的两帧滚动实现
- 移除不必要的 post 延迟操作和手动位置调整
- 删除 WelcomeVM 中未使用的网络请求相关代码
- 移除过时的 MutableLiveData 和 HTTP 相关导入
- 简化 ViewModel 结构，提升代码可维护性

app/src/main/java/com/nova/brain/glass/ui/ChatActivity.kt

@@ -62,14 +62,8 @@ class ChatActivity : BaseListFormLayoutNormalActivity<ChatItem, ChatVM, Activity
         val lastIndex = (recyclerView.adapter?.itemCount ?: 1) - 1
         if (lastIndex < 0) return
         val lm = recyclerView.layoutManager as? androidx.recyclerview.widget.LinearLayoutManager ?: return
-        // 第一帧：确保 lastIndex 进入可视区域
-        lm.scrollToPosition(lastIndex)
-        // 第二帧：layout 完成后，把 lastView 的底部对齐到 RecyclerView 底部
-        recyclerView.post {
-            val lastView = lm.findViewByPosition(lastIndex) ?: return@post
-            val gap = lastView.bottom - (recyclerView.height - recyclerView.paddingBottom)
-            if (gap > 0) recyclerView.scrollBy(0, gap)
-        }
+        // 将最新 item 顶部对齐到 RecyclerView 顶部
+        lm.scrollToPositionWithOffset(lastIndex, 0)
     }
 
     override fun adapter() = object : CommonPagedAdapter<ChatItem>(R.layout.item_chat) {

app/src/main/java/com/nova/brain/glass/viewmodel/WelcomeVM.kt

@@ -1,39 +1,7 @@
 package com.nova.brain.glass.viewmodel
 
-import androidx.lifecycle.MutableLiveData
-import com.nova.brain.glass.repository.Service
-import com.xuqm.base.App
-import com.xuqm.base.di.manager.HttpManager
 import com.xuqm.sdhbwfu.core.viewModel.BaseViewModel
-import io.reactivex.schedulers.Schedulers
-import okhttp3.MediaType.Companion.toMediaTypeOrNull
-import okhttp3.RequestBody
 
 class WelcomeVM : BaseViewModel() {
 
-    val result = MutableLiveData<String>()
-    fun demoGet() {
-        result.value = "GET 请求中..."
-        HttpManager.getApi(Service::class.java).demoGet()
-            .subscribeOn(Schedulers.io())
-            .subscribe({ body ->
-                result.postValue("GET 响应:\n${body.string()}")
-            }, { e ->
-                result.postValue("GET 失败: ${e.message}")
-            }).adds()
-    }
-
-    fun demoPost() {
-        result.value = "POST 请求中..."
-        val json = """{"demo":"post","from":"glass"}"""
-        val body = RequestBody.create("application/json".toMediaTypeOrNull(), json)
-        HttpManager.getApi(Service::class.java).demoPost(body)
-            .subscribeOn(Schedulers.io())
-            .subscribe({ resp ->
-                result.postValue("POST 响应:\n${resp.string()}")
-            }, { e ->
-                result.postValue("POST 失败: ${e.message}")
-            }).adds()
-    }
-
 }