fix: handle Windows rooted negative patterns

[LeulTew]

What is the purpose of this pull request?

Fix Windows rooted absolute exclusions so matching positive and negative patterns cancel with or without a drive letter. Fixes #486.

What changes did you make? (Give an overview)

Resolve only the root of single-slash Windows negative patterns against cwd, preserving glob syntax and explicit drive/UNC roots. Add regression coverage and clarify the Windows pattern documentation.

Validation was local to Windows with Node.js 26.3.0. Linux/macOS, other Node.js versions, and physically mounted secondary drives or UNC shares were not exercised.

Implementation and validation

Absolute negative patterns were compiled without a drive while candidate paths were resolved to drive-qualified paths. Prefixing only the escaped filesystem root reconciles these forms without passing glob expressions through path.resolve.

The public globSync reproduction returned the fixture before the fix and returns [] after it; the drive-qualified control returns [] in both cases. Before the fix, 7 new unit checks and 54 new sync/async/stream checks failed.

• npm run build: passes compilation/type checking, lint, and 292 unit tests.
• SNAPSHOT_SKIP_PRUNING=1 npm run test:e2e -- --reporter dot: 1,449 passing; 9 existing platform-specific pending cases.
• Focused entry-filter and absolute-option suites: 40 and 120 passing respectively, including 12 new unit tests and 69 new public API checks.
• git diff --check: passes.

Coverage includes rooted and drive-qualified positives, negative patterns and ignore, relative/absolute/URL cwd, relative exclusions, nonmatches, output and case settings, hidden files, trailing directory slashes, braces, extglobs, character classes, escaping, and parent segments. Synthetic entry-filter cases exercise distinct drives, literal UNC share metacharacters, explicit UNC roots, and device-drive roots without accessing other drives or network shares.

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