Align URL scanner contract

[alyldas]

Summary

• Keep the URL scanner contract names as backward-compatible shared-shape adapters.
• Export UrlScanHints and keep scanner range and sink shapes aligned with the shared range contract style.
• Replace the local URL masking wrapper with the shared core censorCodePointRanges() helper.
• Add regression coverage for scanner contract typing and public censor wrapper alignment with scanner ranges.

Validation

• npm ci with a temporary npm cache because registry access is unavailable inside the sandbox
• npm run check with a temporary npm cache
• npm run benchmark:url
• npm pack --dry-run with a temporary npm cache

Benchmark Evidence

Baseline origin/main:

• check short clean: 0.0015 avg ms
• check hinted short clean: 0.0009 avg ms
• check long clean: 0.5148 avg ms
• check hinted long clean: 0.5073 avg ms
• censor short clean: 0.0010 avg ms
• censor long clean: 0.5245 avg ms
• censor direct URL: 0.0116 avg ms
• censor late-match URL: 0.6745 avg ms

This branch:

• check short clean: 0.0012 avg ms
• check hinted short clean: 0.0011 avg ms
• check long clean: 0.5248 avg ms
• check hinted long clean: 0.5228 avg ms
• censor short clean: 0.0009 avg ms
• censor long clean: 0.5767 avg ms
• censor direct URL: 0.0139 avg ms
• censor late-match URL: 0.6312 avg ms

The runtime change delegates masking to the existing core helper; scanner matching behavior is unchanged.

Compatibility Notes

• Existing public API remains backward compatible.
• createUrlFilter(), urlFilter(), filter, createUrlScanner(), scanUrlRanges(), and scanUrlRangeMatches() remain available.
• Existing UrlScanInput, UrlRangeScanResult, UrlRangeMatch, and UrlRangeMatchSink names remain available.

Closes #26

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feat: align URL scanner contract
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