perf(fmt): move gitignore matching to Rust

[chenjiahan]

Summary

This PR moves repository .gitignore hierarchy matching for rs fmt from ignore@7.0.6 to Rust while keeping the native binding lazy. It batches each directory across N-API, preserves nested ignore and negation behavior, and removes the JavaScript ignore runtime dependency.

Performance

Warm-filesystem, same-process alternating paired runs; file outputs matched the previous implementation. Negative paired delta means faster.

Repository	Files	Previous median	Current median	Paired median delta
Rstack	550	3.49 ms	3.52 ms	-1.51%
Rsbuild	3,317	30.23 ms	30.97 ms	+3.28%
Rspack	21,140	282.09 ms	152.25 ms	-47.08%

Rsbuild made 1,505 native calls for 5,473 entries (3.64 entries per batch), so reducing fixed per-directory bridge overhead remains the main optimization opportunity.

Known gaps

• Edge-pattern behavior still differs from ignore@7.0.6 for unclosed character classes, braces, Unicode case folding, and escaped trailing spaces.
• Native matcher failures during ignore-file loading still need explicit propagation instead of being treated as read failures.

Validated with pnpm build, pnpm --filter rstack build:native, pnpm test, pnpm check, and cargo fmt --all -- --check.

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