Fix active cleanup pagination shifts

[chubes4]

Summary

• Keep active/no-signal apply continuations on rows that shift into the current page after cleanup metadata writes.
• Covers merged-to-default active/no-signal apply pagination so safe rows are not skipped during bounded cleanup drains.

Testing

• php tests/smoke-worktree-metadata-reconcile.php
• php tests/smoke-worktree-cleanup-cli.php

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Diagnosing the active/no-signal pagination skip, implementing the fix, and drafting smoke coverage; Chris remains responsible for review and release decisions.