engager - Analyze Student Engagement from 'WebVTT' Transcripts

Analyzes participation in course-session transcripts stored in the 'WebVTT' format <https://www.w3.org/TR/webvtt1/>, including transcripts exported by 'Zoom' and similar videoconferencing platforms. Provides tools to load and process transcripts, calculate speaker-level engagement metrics, create privacy-supporting plots and exports, and perform reviewable exact name matching against course rosters. Structured-field masking and technical privacy-review helpers support local review but do not determine legal or institutional compliance.