Authorize fixture-only Worktrees reclaim for beta16 Dev Box qualification

[coneilen]

Summary

The operator authorized packaged Worktrees reclaim qualification. Before this,
the beta14–beta16 handoffs allowed only inspection, so reclaim (#651) and the
#560 Worktrees rows could not be qualified on the Dev Box. This records the new
handoff revision beta16-r2. Its candidate is unchanged; only Approval A's
Worktrees scope differs.

Changes

• Record GraphCode-DevBox-Handoff-0.1.78-windows.beta16-r2:
  • the candidate ZIP, source custody and plan are byte-identical to the
    original beta16 handoff;
  • Approval A's Worktrees decision is now
    AvailableReclaimOnDisposableFixtures;
  • the original handoff is retained unchanged.
• Record what the Dev Box prompt's reclaim gate requires:
  • a cancel that changes nothing;
  • reclaim of one landed row and one locked row, with exact
    removed-branches.log entries;
  • dirty-row protection;
  • branch recovery from the logged tip;
  • untouched controls and sentinels.
• UIA live gate times out (GetFirstChild 0x80131505) after overview-lane Worktrees click #560 and the parity rows stay Partial.

Test plan

RED: Get-FileHash of the original beta16 handoff approvals\approval-a.json and README -> worktrees.decision AvailableInspectionOnly; reclaim NotAuthorized
GREEN: hashes.sha256 reverify of GraphCode-DevBox-Handoff-0.1.78-windows.beta16-r2 -> 8/8 verified; worktrees.decision AvailableReclaimOnDisposableFixtures
REGRESSION: Get-FileHash comparison of candidate ZIP, custody ZIP and plan between beta16 and beta16-r2 -> byte-identical; original beta16 hashes.sha256 still 78ea03fada20125138911a2221e34b5d719ebee3d1d6cac8139a62470f0777a6

• hashes.sha256 for the r2 handoff:
  cbee6d29eef869cd979e6245e7a82c6c7f10ba4aa5a00011d3670e24edaed064.
• Not claimed: no reclaim has been run on a packaged build yet.
• No tag or release was pushed or published.
• macOS make test and make check were not run; this is a
  documentation-only change.

Checklist

• I have read the Contributing Guidelines
• I have signed off my commits (git commit -s) per the DCO
• Tests pass locally (make test)
• Code follows the existing style (make check)
• I added the test/contract before the implementation and observed the intended RED failure