fix(scoring): harden label glob translation

[JSONbored]

Motivation

• Translating repo-configured label multiplier keys to JavaScript RegExp could throw or mis-match for certain fnmatch-style bracket expressions (e.g. [z-a], [!], [^x]) and thereby crash the scoring preview or produce incorrect multiplier matches.
• The upstream/validator uses Python fnmatch semantics which tolerate these cases; the preview must preserve parity and fail-safe behavior for untrusted registry keys.

Description

• Harden labelPatternToRegExp to mirror Python fnmatch edge-case behavior by treating empty/bare bracket classes (like [] or [!]) as literals and by emitting a never-match fragment ((?!)) for descending/invalid ranges instead of compiling a throwing RegExp.
• Preserve negation semantics for [^x]/[!x] while avoiding accidental RegExp caret-interpretation for literal leading ^ in classes.
• Add small helpers escapeRegExpLiteral and hasDescendingCharacterRange to support safe translation and range validation.
• Add unit test coverage in test/unit/scoring.test.ts for [^x], [z-a], and [!] patterns and other bracket-class edge cases to guard against regressions.

Testing

• Ran the focused unit test: npx vitest run test/unit/scoring.test.ts -t "matches configured label keys" and the full file: both completed and passed (72 tests passed).
• npm run typecheck completed with no type errors.
• npm run test:coverage and npm run test:ci were started during validation but did not complete in this environment (coverage run was terminated due to local runtime constraints and test:ci was interrupted during coverage); the unit-level tests validating the fix passed.
• npm audit --audit-level=moderate could not complete due to the registry audit endpoint returning 403 in this environment.

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Codex Task

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.42%. Comparing base (0574c0f) to head (06044d4).
⚠️ Report is 45 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1450   +/-   ##
=======================================
  Coverage   95.42%   95.42%           
=======================================
  Files         193      193           
  Lines       21026    21037   +11     
  Branches     7614     7619    +5     
=======================================
+ Hits        20064    20075   +11     
  Misses        383      383           
  Partials      579      579           

Files with missing lines	Coverage Δ
src/scoring/preview.ts	99.06% <100.00%> (+0.03%)	⬆️

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