v0.63.6

Changelog

• 9a2f1cc Bump version to v0.63.6
• 0e308ff Merge pull request #627 from zzet/fix/mutation-commit-receipt
• fa94836 Merge pull request #628 from zzet/fix/release-checksums-signature
• 7127a89 Merge pull request #629 from zzet/fix/gitignore-literal-metacharacters
• 6191952 ci(release): verify every published signature against its artifact
• 0cd9dcb excludes: treat regexp metacharacters in ignore patterns as literal text
• 2757802 fix(mcp): expose the disk-commit boundary when a mutating tool is abandoned
• cc86fda fix(release): re-sign checksums.txt after appending the windows entry
• 0bec99a indexer: report a repo that indexed no files instead of reporting success
• 03d2693 test(indexer): pin the reported repro — pandas' .gitignore against a real index pass