Searching a directory tree with regex

When to use

• Where a caller would otherwise reach for rg or grep -rn: faster and structured.
• Pre-step before shell::fs::sed to preview what would be rewritten.
• Cross-file search inside a worker without spawning a process.

Notes

• include_glob and exclude_glob are arrays of glob strings (e.g. ["**/*.rs"], ["**/target/**"]). The keys are singular _glob, not plural _globs.
• The flag is ignore_case, not case_insensitive.
• Multiline mode is off by default; encode (?m) inside the pattern when multiline anchoring is needed.
• When max_matches is hit, truncated: true is set and the walk stops. Tighten the pattern or narrow path instead of bumping the cap blindly.
• Binary files are skipped automatically. The wire FsMatch has no column field; the legacy file alias is accepted on the deserialiser side but the response always renders as path.
• Same jail and denylist rules as shell::fs::ls.