Add a CI check for compat flag dates

[vicb]

Make sure compat flags are not enabled before 7d

• checked on PR creation
• checked daily to prevent issue with long running PR.

Generated by OpenCode:

Summary

• Added a Cap’n Proto schema (FlagInfoList) and JSON dump tool for compatibility flags using capnp::JsonCodec.
• Added unit tests covering known flags, date formatting/consistency, duplicates, and JSON encode/decode.
• Added PR-time and daily GitHub workflows to enforce new compatibility dates are at least N days in the future, with configurable min_days and an urgent-compat-flag bypass label.

[github-actions]

The generated output of @cloudflare/workers-types matches the snapshot in types/generated-snapshot 🎉

[codspeed-hq]

CodSpeed Performance Report

Merging this PR will improve performance by 13.32%

_{Comparing vicb/compat-date-check (89624af) with main (08419cb)}

Summary

⚡ 1 improved benchmark
✅ 69 untouched benchmarks
⏩ 129 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	Encode_ASCII_32[TextEncoder][0/0/32]	3.3 ms	2.9 ms	+13.32%

Footnotes

1. 129 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩