Record the Windows beta17 preview candidate

[coneilen]

Summary

Record the immutable, unpublished Windows beta17 preview candidate and its
LFS-aware Dev Box handoff.

Beta16 is failed and superseded: Show in Graph ran Review attention through
the hidden Needs-you rail. #658 fixes that, and #659 fixes the collapsed panel
covering Show in Graph.

Approval A keeps fixture-only Worktrees reclaim. All runtime qualification
gates remain open.

Changes

• Record source/tag/package/payload/executable/provider/toolchain identities for
  0.1.78-windows.beta17 at 4ab2fcf4cebee0945ffa4af067e7a9a650634a46.
• Record the Keep Show in Graph and the loop bar on the open Windows loop #658 and Keep Show in Graph clear of the collapsed loop panel's expand control #659 root causes and the passing full local validation.
• Correct the parity count. A recount at each candidate source shows 59/39 for
  beta14–beta16, not the recorded 60/38, and 58/40 now after Keep Show in Graph clear of the collapsed loop panel's expand control #659.
• Update the Exact artifact gate wording to the reclaim approval.
• Record custody, the offline restore (43/43 LFS) and the 8/8 handoff.
• Move beta16 to history. Beta1–beta16 and both beta16 handoffs are unchanged.

Test plan

RED: PR 658 and 659 native-linked App regressions before their fixes -> Show in Graph click ran cycle_attention and the collapsed expand control overlapped Show in graph
GREEN: Tools\windows\validate.ps1 -Task windows-shell -SkipTrayLive -ShellValidationRoot C:\v7 at 4ab2fcf -> VALIDATE_EXIT=0; 55/55 sections; App 888/888; scrubbed 5/5; real daemon round trip PASS; live UIA gate PASS
REGRESSION: Tools\windows\release.ps1 -Tag 0.1.78-windows.beta17 -> repository verify 1 PASS; extracted setup verify 1 PASS; payload 50; binary reports available; packaged scrubbed startup 5/5

• The RED line summarizes the evidence in Keep Show in Graph and the loop bar on the open Windows loop #658 and Keep Show in Graph clear of the collapsed loop panel's expand control #659. I did not reproduce it
  locally.
• Parity recount: rows ending | Validated | and | Partial | in
  investigation/ui-parity-matrix.md.
  • At af3d0061 (beta13): 60/38.
  • At d9fe093c, 4151ab17 and d75bb952 (beta14–beta16): 59/39.
  • At 4ab2fcf4: 58/40, total 98.
• Source custody Create/Verify passed with 43 objects for 43 files. The
  file-only offline restore gave exact detached HEAD/tag, zero remotes, clean
  status and 43/43 materialized LFS files.
• Handoff inventory: 8/8 verified; hashes.sha256 SHA-256
  432adad3c14ec27cb04876bacf432656560a3b408d3eaef22f8a6ef01696b6e8.
• Not claimed: Dev Box Show in Graph or reclaim results, backend, destructive,
  Nod, dump or publication evidence.
• 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