Task 415: Add Dialogue Temporal Integrity Tests

Status: DONE

Summary

Dialogue data files (epXX_dialogue.json) have structural validation (valid speakers, scenes, schema version) but lack temporal integrity checks. Add tests for: timestamp monotonicity within scenes, dialogue entries falling within their scene boundaries, scene interval ordering, and cross-episode speaker ID consistency for recurring characters.

Rationale

• Dialogue data is a fundamental source of truth for the project
• Timestamps drive video link generation and quote citation
• Out-of-order entries or entries outside scene boundaries would cause incorrect citations
• CLAUDE.md: "Timestamp accuracy matters" and "Transcription-report sync"
• Cross-episode speaker consistency prevents silent divergence of IDs for recurring characters

Plan

1. Add per-scene dialogue timestamp monotonicity test
2. Add dialogue-within-scene-boundary containment test
3. Add scene interval ordering and non-overlap test
4. Add cross-episode recurring speaker ID consistency test
5. Run tests, fix any data issues found, commit