[Homebrew/Deploy] Ship the exact rev22 lazy shell on Pages

[brandonpayton]

Why

The current Pages workflow asks for a sealed Homebrew selection, but
the checked-in selection is still honestly pending. Deployment run
30834451743 therefore failed before it built the site.

The exact rev22 ABI 42 shell is already public. It starts mostly lazy,
activates Homebrew on first use, and reads bottles from an immutable
public mirror. Rebuilding unrelated gallery images should not block
deploying that working shell.

The host fix in #1209 also changed the source identity of six
conventional gallery artifacts. Their already-published output bytes
did not change. This PR pins those exact archives and output members by
digest so Pages can reuse them without weakening the normal
stale-artifact checks.

What changes

• Fetch the exact public rev22 shell and Homebrew bootstrap anonymously.
• Verify each archive and extracted member by byte count and SHA-256
  digest.
• Preserve five exact gallery images that are already deployed.
• Rebind six unchanged conventional outputs to their current source
  identity.
• Assemble the complete browser product around those locked bytes.
• Forward the /kandelo/ base path into the controlled Chromium test
  shell.
• Require Chromium to complete the in-guest brew proof before
  deployment.
• Record the temporary lane and its removal condition in the
  documentation.

This is a temporary compatibility lane, not a new path convention. Rev22
uses /home/linuxbrew/.linuxbrew; the final Kandelo path remains
/opt/kandelo/homebrew. The lane is removed when the canonical shell is
deployable.

This PR is stacked on #1209. Current host code must honor the immutable
descriptor prefix so it can consume the older shell truthfully.

Validation

• Exact shell, bootstrap, mirror plan, gallery images, and compatibility
  outputs were fetched anonymously and verified by digest.
• Browser dependency preparation resolved 58 variants and skipped only
  the explicitly locked transition inputs; it performed no package
  rebuilds.
• The workflow-equivalent Vite production build passed and emitted the
  exact locked shell and bootstrap.
• The strict public Chromium in-guest Homebrew proof passed in 25.0
  seconds.
• Pages deployment contract and mutation suite passed.
• Transitional lock tests passed: 3/3.
• Complete Homebrew shell contract passed: 48/48 focused Node tests
  plus all shell workflow probes.
• git diff --check passed.

The earlier live Pages proof also passed in 42 seconds. Its dated JSON
evidence remains committed for comparison.