Record unpublished Windows beta18 preview candidate

[coneilen]

Summary

Record the immutable, unpublished Windows beta18 preview candidate and its
LFS-aware Dev Box handoff.

Beta17 failed and is superseded by its Dev Box findings, fixed in #662–#665:

• Uninstall left a partial installation while loop zmx.exe hosts were live.
• The earlier project stopped updating after Ctrl+O opened a second one.
• A stale terminal surface was drawn over the sidebar.
• New Tab had the wrong UIA tab count and the wrong working directory.
• Node IDs were timestamps behind a constant prefix.
• The Rename dialog opened without keyboard focus.

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.beta18 at 880e6a389a66f5fc4dbc9da0830673713f3482be.
• Record the Refuse Windows uninstall while GraphCode runs and make removal all-or-nothing #662–Fix Windows node ids and text dialog initial focus (beta17 Dev Box findings) #665 findings and the passing full local validation.
• Record the parity count: Fix stale terminal surfaces, New Tab UIA/cwd, and loop opens after deleting an attached loop #663 moved Tab pills to Partial, so it is 57/41.
• Record custody, the offline restore (43/43 LFS) and the 8/8 handoff.
• Point the current-candidate references (Exact artifact gate, publication
  record, plan binding, Windows first-run onboarding blocks daemon connection; main window shows "Disconnected" and dialog has no UIA tree #556 orchestration item) at beta18.
• Move beta17 to history. Beta1–beta17 and their handoffs are unchanged.

Test plan

RED: PR 662-665 regressions before their fixes -> uninstall partial removal with live zmx hosts, earlier project graphChanged dropped by the hello filter, stale surface at 0,0 480x240, timestamp node ids and unfocused Rename dialog
GREEN: Tools\windows\validate.ps1 -Task windows-shell -SkipTrayLive -ShellValidationRoot C:\v7 at 880e6a3 -> VALIDATE_EXIT=0; 55/55 sections; App 899/899; scrubbed 5/5; real daemon round trip PASS; live UIA gate PASS
REGRESSION: Tools\windows\release.ps1 -Tag 0.1.78-windows.beta18 -> 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 Refuse Windows uninstall while GraphCode runs and make removal all-or-nothing #662–Fix Windows node ids and text dialog initial focus (beta17 Dev Box findings) #665. I did not reproduce it
  locally.
• Parity recount: rows ending | Validated | and | Partial | in
  investigation/ui-parity-matrix.md at 880e6a38 give 57/41, total 98. Only
  Fix stale terminal surfaces, New Tab UIA/cwd, and loop opens after deleting an attached loop #663 changed a status.
• The daemon and CLI are byte-identical to beta17. The shell, the generated
  Setup script and the rebuilt zmx differ. zmx is built from the same pin, and
  that provider build has never been byte-reproducible.
• 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
  7ae54ffb554bb44248841a65158079f1506cc1be36109f5972a9c77386e31f03.
• Not claimed: Dev Box results, the installed Uninstall refusal, backend,
  destructive, Nod, dump or publication evidence. validate.ps1 -Task packaging
  was not run locally; it ran green in Refuse Windows uninstall while GraphCode runs and make removal all-or-nothing #662's CI.
• 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