fix(kernel,desktop): Core Chain Hardening 穷尽审计 7 项修复

审计发现 1 CRITICAL + 4 HIGH + 4 MEDIUM + 4 LOW, 修复如下:

CRITICAL:
- TS seam 测试改为 JSON round-trip 验证 (12 测试覆盖 10 事件类型)

HIGH:
- post_conversation_hook 拦截路径 driver=None 加 debug 日志
- schedule intercept channel send 失败回退 LLM (return Ok(None))

MEDIUM:
- DeltaBuffer.flush() 先 mutation 再 clear, 防止异常丢数据
- ModelsAPI.tsx 去重: 改用 model-config.ts 导出 (消除 2 函数+1 接口+2 常量)
- boot_with_driver docstring 记录跳过 agent 恢复

TypeScript 0 错误, Rust 76 kernel 测试通过, TS 12 seam 测试通过

desktop/src/store/chat/streamStore.ts

@@ -172,8 +172,6 @@ class DeltaBuffer {
     this.timer = null;
     const text = this.text;
     const think = this.think;
-    this.text = '';
-    this.think = '';
     if (text || think) {
       this.chat.updateMessages(msgs =>
         msgs.map(m => {
@@ -186,6 +184,8 @@ class DeltaBuffer {
         })
       );
     }
+    this.text = '';
+    this.think = '';
   }
 
   clear() {