feat(planner): finding 当场唤醒 + planner N 秒心跳触发(任务参数,默认5min)

触发机制补两条(见 docs/planner-trigger-impl-plan.md)：

1) finding 当场唤醒：worker 飞行中 report_finding 落库即唤醒本任务 planner，
   不再等 worker 整趟收工才反应。
   - worker.Execute 加 notify 入参并 SetNotify(补上 worker toolset 之前缺失的接线)
   - addFinding 写 KindFinding 成功后调 notify(只对 finding,不对 fact)
   - engine 两处 worker.Execute 调用传 t.Notify

2) planner N 秒心跳：距上轮规划结束/任务开始满 N 秒且期间无触发 → 触发一轮，
   兜底卡死 + 唤醒去监督飞行中的 worker(steer/kill) + 周期复查。
   - plannerLoop 重构为 runRound 闭包 + 三臂 select(ctx/notify/heartbeat)
   - 心跳在 loop 入口臂 = 从任务 start 计时(覆盖 seed 跳过首轮)，每轮结束重臂
   - 新增任务参数 plan_heartbeat_seconds，下限=默认=300(5min),低于自动抬到300
   - DB 迁移：schema.sql 加列 + ALTER ADD COLUMN IF NOT EXISTS 补旧库
   - 全链路接线：db.CreateTask/manager/server HTTP/orchestration spawn_task
   - 前端：api.createTask 传参 + 建任务表单新增"planner 心跳(分钟)"字段

server/manager.go

@@ -36,9 +36,10 @@ type Task struct {
 	LLMProfileID *int64 `json:"llm_profile_id,omitempty"` // 指定运行本任务 planner/worker 的 LLM 配置;nil=用全局激活配置
 	Status       string `json:"status"`                   // persisted lifecycle status (done/failed/timeout 为终态；空/其它则由运行态推导)
 	// 任务级超时(见 docs/任务级超时与收尾设计.md)。DeadlineAt/FirstRunAt 为 unix 秒,0=未设/未运行。
-	TimeoutSeconds int                    `json:"timeout_seconds"`
-	FirstRunAt     int64                  `json:"first_run_at,omitempty"`
-	DeadlineAt     int64                  `json:"deadline_at,omitempty"`
+	TimeoutSeconds       int   `json:"timeout_seconds"`
+	PlanHeartbeatSeconds int   `json:"plan_heartbeat_seconds"` // planner 心跳触发间隔(秒)
+	FirstRunAt           int64 `json:"first_run_at,omitempty"`
+	DeadlineAt           int64 `json:"deadline_at,omitempty"`
 	Store          *pgdb.ExplorationStore `json:"-"`
 	Guard          *guard.Guard           `json:"-"`
 	notify         chan struct{}
@@ -459,15 +460,16 @@ func taskFromPG(pt *pgdb.Task, store *pgdb.ExplorationStore, ic *intercept.Inter
 		Description: pt.Description, Goal: pt.Goal, CreatedAt: pt.CreatedAt.Unix(), Paused: pt.Paused,
 		CompletedAt: unixOrZero(pt.CompletedAt), Status: pt.Status, ParentRef: pt.ParentRef,
 		LLMProfileID:   pt.LLMProfileID,
-		TimeoutSeconds: pt.TimeoutSeconds, FirstRunAt: unixOrZero(pt.FirstRunAt), DeadlineAt: unixOrZero(pt.DeadlineAt),
+		TimeoutSeconds: pt.TimeoutSeconds, PlanHeartbeatSeconds: pt.PlanHeartbeatSeconds,
+		FirstRunAt: unixOrZero(pt.FirstRunAt), DeadlineAt: unixOrZero(pt.DeadlineAt),
 		Store: store, Guard: guard.NewWithInterceptor(ic), notify: make(chan struct{}, 1),
 	}
 }
 
 // CreateTask creates a task + its exploration and makes it active.
 // timeoutSeconds is the task-level wall-clock budget (0 = 不限时).
-func (m *Manager) CreateTask(description, goal string, llmProfileID *int64, timeoutSeconds int) (*Task, error) {
-	pt, err := m.pg.CreateTask(description, goal, llmProfileID, timeoutSeconds)
+func (m *Manager) CreateTask(description, goal string, llmProfileID *int64, timeoutSeconds, planHeartbeatSeconds int) (*Task, error) {
+	pt, err := m.pg.CreateTask(description, goal, llmProfileID, timeoutSeconds, planHeartbeatSeconds)
 	if err != nil {
 		return nil, err
 	}