Fix S890 Thai decoding + add Amazon MEC XML metadata QC

feat: 3-tier sensitive term routing — OFFENSIVE skip AI, POTENTIALLY_OFFENSIVE reviewed by AI, NEUTRAL skipped

fix: downgrade lowers severity by one level, not to arbitrary AI choice

fix: skip NEUTRAL sensitive terms — they are reference notes, not actionable flags

fix: QC matrix output changed from DOCX to XLSX (ExcelJS)

fix: PMW writer/reader roundtrip — text now preserved through SRT→PMW conversion

feat: QC Issue Matrix DOCX generation (identical to qc-matrix skill)

feat: KNP terminology consistency check + AI translator credit detection

feat: Netflix format checks — CPL, max lines, duration, translator credits

fix: boundary-aware sensitive term matching — eliminate substring false positives

fix: remove \b word boundaries for ALL languages — 100% sensitive term detection

fix: sensitive term matching for CJK/Thai/Arabic (no \b word boundary)

feat: parallel file processing with global semaphore (max 50) + timecodes in XLSX report

feat: real-time log panel for QC pipeline

feat: add GCP Vertex AI auth for Claude (alongside direct API key)

GTS-X: Full HITL editor + QC + file converter for HuggingFace Spaces

Fix TTML reader: frame-count timecodes, frameRateMultiplier, entity decoding

Initial commit — GTS Modern subtitle converter