fix: 修复多轮对话400/Provider通知反复弹出/浏览器环境隔离三大缺陷

1. 多轮对话第二次发消息 AI 不响应 (CRITICAL)

handlers.ts: 保存 tool 结果消息到数据库，DeepSeek API 要求 assistant 有 tool_calls 时后续必须有对应 tool 结果消息

openai-format.ts: assistant 有 tool_calls 时 content 设为 null (API 规范，空字符串会导致 400)

agent-store.ts: 前端加载历史时过滤 tool 消息，避免冗余卡片

2. Provider 切换通知每次发消息都弹出

main.ts: reloadAdapter 添加配置签名比较 (lastConfigSig)，配置未变化时幂等返回 true，不再重建 adapter 或发 toast

3. 浏览器工具无环境隔离

browser-window-manager.ts: 独立 partition 隔离 Cookie/存储; 恢复 webSecurity，CORS 通过 webRequest 处理; setWindowOpenHandler 拦截 window.open; 并发互斥锁串行化 open 调用; destroy() 改用 win.destroy() + clearStorageData 清理残留

src/stores/agent-store.ts

@@ -153,16 +153,20 @@ export const useAgentStore = create<AgentState>((set, get) => ({
           attachments?: Array<{ id: string; name: string; type: string; size: number; preview?: string; textContent?: string }>;
           iteration?: number;
           timestamp: number;
-        }>).map((m) => ({
-          id: m.id,
-          role: m.role as ChatMessage['role'],
-          content: m.content,
-          reasoningContent: m.reasoningContent,
-          toolCalls: m.toolCalls as ToolCallInfo[] | undefined,
-          attachments: m.attachments as AttachmentInfo[] | undefined,
-          iteration: m.iteration,
-          timestamp: m.timestamp,
-        }));
+        }>)
+          // v0.3.0 修复: 过滤掉 tool 消息 — tool 结果已包含在 assistant 消息的 toolCalls 中
+          // 独立的 tool 消息只用于 LLM API 上下文，不需要在前端显示为独立卡片
+          .filter((m) => m.role !== 'tool')
+          .map((m) => ({
+            id: m.id,
+            role: m.role as ChatMessage['role'],
+            content: m.content,
+            reasoningContent: m.reasoningContent,
+            toolCalls: m.toolCalls as ToolCallInfo[] | undefined,
+            attachments: m.attachments as AttachmentInfo[] | undefined,
+            iteration: m.iteration,
+            timestamp: m.timestamp,
+          }));
         set({ messages });
       }).catch((err) => { console.error('[AgentStore]', err); });
     }