[jimi-21]

Summary

• support apostrophe separators in C23 decimal, octal, hexadecimal, and binary integer literals
• prevent separators from being interpreted as the start of character literals
• add regression coverage for all four bases, integer suffixes, and ordinary integer literals

Fixes #4289.

Validation

• go test ./...
• go generate ./runtime
• go build ./cmd/micro
• go test ./internal/...
• go test ./cmd/...
• gofmt -l . (no output)

AI assistance

This contribution was prepared with Kimi Code assistance, including the regex changes and regression tests. The change and verification results were reviewed before submission.

[Andriamanitra]

this is completely nonsensical AI slop