fix: --glob panics on a pattern gobwas/glob rejects

[VXNCXNX]

What's broken

--glob panics on a pattern that doublestar accepts and gobwas/glob does not.

$ vale --glob='[a-]*.md' .
panic: expected close range character

goroutine 36 [running]:
github.com/gobwas/glob.MustCompile(...)
	github.com/gobwas/glob@v0.2.3/glob.go:57
github.com/errata-ai/vale/v3/internal/glob.Glob.Match(...)
	internal/glob/glob.go:26

The panic happens inside a goroutine partway through the walk, so it aborts the run with a stack trace rather than reporting a bad flag value.

After:

$ vale --glob='[a-]*.md' .
expected close range character

Same exit code, no stack trace.

Cause

NewGlob and Match use two different glob engines. Validation happens in NewGlob via doublestar.PathMatch, but the actual matching in Match compiles the pattern with glob.MustCompile. The two grammars disagree on character ranges, so a pattern can pass construction and then panic on first use.

MustCompile was also being called once per candidate file, since Match compiled on every call.

The fix

Compile in NewGlob with glob.Compile and store the result on the struct. An invalid pattern is now an error at construction, where the caller can report it, and Match uses the already-compiled matcher.

** patterns keep going through doublestar, which is what handled them before. Those leave compiled nil, and Match branches on that rather than re-testing the pattern string.

Behaviour on valid patterns is unchanged. Same tree, before and after binaries, identical output for *.md, **/*.md, !*.md, {*.md,*.txt}, docs/** and *.

Verification

TestInvalidGlob in internal/glob/glob_test.go covers [a-] and [a-b-c], the range family where the two engines diverge.

A glob-invalid case in testdata/e2e/config-flags.yaml, next to the existing glob-negated-dir case, pins the CLI behaviour end to end. Its golden was filled with the repo's own go test ./internal/e2e -update, not by hand.

Reverting glob.go while keeping both fails them, and nothing else:

--- FAIL: TestInvalidGlob
    glob_test.go:44: [a-]: expected an error, got {Pattern:[a-] Negated:false}
    glob_test.go:44: [a-b-c]: expected an error, got {Pattern:[a-b-c] Negated:false}
--- FAIL: TestScenarios/config/flags/glob-invalid

go test ./internal/glob/... ./internal/e2e/... is green with the fix. golangci-lint run ./internal/glob/... reports 0 issues and gofmt -l is clean.

Disclosure: written with AI assistance (Claude Code). I built both binaries from this tree, reproduced the panic and the fixed output with the commands above, checked the six real-world patterns for parity, and ran the revert check myself.