fix: decode common entities and identify malformed metadata

[rogerchappel]

Summary

• decode common semicolon-terminated HTML symbol references, including ™, €, and typographic quotes, while preserving unknown and unterminated references
• wrap malformed fixture metadata syntax errors with the exact meta.json path and native parser context
• cover directory-level fixture discovery diagnostics and document the executable behavior

Commits

• 14f1429 test: cover named entities and metadata parse paths
• 831f921 fix: decode common entities and identify malformed metadata
• 50441c9 docs: describe entity and metadata diagnostics

Verification

• npm ci
• npm run release:check (39 tests plus syntax, build, smoke, package smoke, and release contract)
• git diff --check origin/main...HEAD

All commit authors and committers are Roger Chappel <miscanalysis@gmail.com>.

[rogerchappel]

Automated merge note

Triage class: auto-merge

Summary: Adds focused standards-aligned decoding for common semicolon-terminated named HTML entities, preserves unknown references, and improves malformed meta.json diagnostics with exact paths and regression coverage.

Checks run: CI / test — SUCCESS; local npm ci, npm run release:check (13/13 tests, syntax check, build, smoke, package dry-run), and git diff --check; branch protection verified (one approving review required; no required status checks); all authors and committers verified as Roger Chappel miscanalysis@gmail.com.

Rebased/CI-repaired: no.

Verified head SHA: 50441c9.