Add recording policy and time-range checks

This change adds a recording policy layer that enforces time-window eligibility and excluded title keywords before probing and before recording. It updates the streamer API to surface reasons like OutOfSchedule and TitleExcluded, clamps ffmpeg/segment durations to the configured window, and exposes the last rejection reason from the worker state for the frontend.

app/(app)/streamers/page.tsx

@@ -69,6 +69,9 @@ export default function Home() {
       case 'OutOfSchedule':
         statusTag = <Tag color="green">非录播时间</Tag>
         break
+      case 'TitleExcluded':
+        statusTag = <Tag color="orange">标题已排除</Tag>
+        break
       case 'Pause':
         statusTag = <Tag color="pink">暂停中</Tag>
         break