feat(agent): Agent 工作台 - 计划插话记忆、统一模型选择器并修复摘要与视频入库

将计划清单、运行中插话和个人记忆接入云端 Agent；全站模型选择器统一为左右二级菜单。画布摘要按预算截断不再整轮拒绝，首页视频未知宽高可入库。README 补充贡献者 morrow。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/internal/database/schema.go

@@ -19,6 +19,8 @@ func Models() []any {
 		&model.CloudAgentExecution{},
 		&model.CloudAgentCanvasMutation{},
 		&model.AgentProfile{},
+		&model.AgentLesson{},
+		&model.AgentMemorySetting{},
 		&model.User{},
 		&model.AuthSession{},
 		&model.UserIdentity{},