feat: Round 5 - Memory Service, Tool Engine, Call Records, Thinking Logs

- Fix: Session history flash (race condition + WS guard)
- Fix: Chat background overlay + sidebar transparency
- Fix: IoT device control (Chinese action names, status field)
- Feat: Independent memory-service (port 8091, 13 endpoints)
- Feat: Independent tool-engine service (port 8092, 13 tools)
- Feat: Tool call logs with paginated DevTools panel
- Feat: Thinking log records with DevTools panel
- Feat: Future development roadmap document
- Chore: Updated .gitignore, go.work, DevTools config
- Chore: 5-service health check, project review docs

backend/tool-engine/internal/model/tool.go

@@ -0,0 +1,37 @@
+package model
+
+// ToolDefinition 工具定义（用于 LLM function calling）
+type ToolDefinition struct {
+	Name        string                 `json:"name"`
+	Description string                 `json:"description"`
+	Parameters  map[string]interface{} `json:"parameters"`
+}
+
+// ToolCall 工具调用请求
+type ToolCall struct {
+	ID        string                 `json:"id"`
+	Name      string                 `json:"name"`
+	Arguments map[string]interface{} `json:"arguments"`
+}
+
+// ToolResult 工具执行结果
+type ToolResult struct {
+	ID     string `json:"id"`
+	Output string `json:"output"`
+	Error  string `json:"error,omitempty"`
+}
+
+// ExecuteRequest 单个工具执行请求
+type ExecuteRequest struct {
+	Arguments map[string]interface{} `json:"arguments"`
+}
+
+// BatchExecuteRequest 批量执行请求
+type BatchExecuteRequest struct {
+	Calls []ToolCall `json:"calls"`
+}
+
+// BatchExecuteResponse 批量执行响应
+type BatchExecuteResponse struct {
+	Results []ToolResult `json:"results"`
+}