Propagate .ai/.claude setup correctly and preserve symlink modes in Copilot sync workflows

[Copilot]

Summary

Propagation was only syncing .github Copilot artifacts and writing all files as regular blobs, which broke .claude -> .ai symlink propagation from source repos like Fundamentals.
This change extends synced path coverage to .ai/ and .claude/ and preserves Git tree entry mode during sync/propagate/bootstrap updates.

Added

• Synced artifact coverage for .ai/ and .claude/ paths across all Copilot sync flows.
• Documentation entry for .ai/ and .claude/ as synchronized artifacts in README.md.

Changed

• Updated path filters in:
  • .github/scripts/propagate-copilot-instructions.sh
  • .github/scripts/sync-copilot-instructions.sh
  • .github/scripts/bootstrap-copilot-sync.sh
• Up-to-date checks now compare both blob SHA and file mode.
• Tree creation now writes source mode dynamically (100644, 100755, 120000) instead of forcing 100644.

Fixed

• Fixed failure to propagate AI setup directories from source repositories.
• Fixed incorrect handling of symlinked .claude/* entries by preserving symlink mode (120000) in target repos.

# Before
.tree += [{path: $p, mode: "100644", type: "blob", sha: $s}]

# After
.tree += [{path: $p, mode: $m, type: "blob", sha: $s}]

Removed

• None.

Security

• None.

Deprecated

• None.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/Cratis/Fundamentals/git/trees/HEAD
  • Triggering command: /usr/bin/curl curl -fsSL REDACTED (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)