Record the beta3 Windows preview candidate

[coneilen]

Summary

Records the verified local 0.1.78-beta3 Windows preview candidate and its LFS-aware offline source custody without claiming Dev Box/runtime qualification or publication.

Changes

• Makes beta3 the active frozen candidate and preserves beta1/beta2 as immutable superseded records.
• Records exact package, executable, toolchain, provider, handoff, evidence-inventory, and source-custody identities.
• Marks Exact artifact complete while keeping the other six gates open, Worktrees guarded/deferred, UIA live gate times out (GetFirstChild 0x80131505) after overview-lane Worktrees click #560 open, and Bound UIA Worktrees gate traversal #587 harness-only.
• Replaces the failed bare-bundle custody path with the verified custody ZIP and included offline restore script.

Test plan

RED: PowerShell beta3/LFS release-plan assertion against investigation\windows-preview-release-plan.md -> missing=0.1.78-beta3, GraphCode-source-custody.zip, Git LFS 3.7.1, 43 objects / 43 tracked files / 43 materialized files; legacy-bare-bundle=True
GREEN: PowerShell beta3/LFS release-plan assertion against investigation\windows-preview-release-plan.md -> beta3-markers=7/7; legacy-bare-bundle=False
REGRESSION: PowerShell ledger parser; pwsh -NoProfile -File Tools\windows\Tests\PreviewCore.Tests.ps1 -Case All; pwsh -NoProfile -File Tools\windows\validate.ps1 -Task privacy; git diff --check origin/main...HEAD; git diff --name-only origin/main...HEAD -> ledger 98 total/62 Validated/36 Partial/0 other; PreviewCore 37/37 passed; privacy passed; diff check clean; one file changed

make test and make check were not run because this is a Windows investigation-document-only change. No product code, tests, tooling, candidate artifacts, qualification plans, handoff files, tags, or parity-ledger rows changed.

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