Validate minimum coverage values strictly

[rogerchappel]

Summary

• add full-string decimal parsing for --min-coverage
• reject numeric prefixes and non-decimal syntax with the existing concise error
• cover valid boundaries/fractions and malformed CLI/unit cases
• document the accepted 0–100 decimal range

Commits

• 5d38fbb test: cover strict minimum coverage parsing
• cfe5202 fix: validate minimum coverage as a decimal
• 41599e1 docs: define minimum coverage input syntax

Verification

• npm ci
• npm run release:check (118 tests; audit, typecheck, lint, coverage, smoke, validation, package smoke)
• git diff --check origin/main...HEAD
• author and committer identity verified for every commit as Roger Chappel <miscanalysis@gmail.com>

[rogerchappel]

Automated merge note

Triage class: auto-merge

Summary: Strictly validates decimal --min-coverage values, with unit/CLI regression coverage and documentation (6 files, +46/-2).

Checks run: GitHub Actions CI test on Node 20.19.0, 22, and 24 completed SUCCESS; worker verification recorded npm ci, npm run release:check (118 tests plus audit, typecheck, lint, coverage, smoke, validation, package smoke), and git diff --check origin/main...HEAD. Final complete diff, mergeability, one-review branch protection, Roger Chappel identity, and immutable head were re-verified.

Rebased/CI-repaired: No.

Verified head SHA: 41599e1aacea55417b0fb08896152b1a428ace2e.