Phase 1: ParseTranscript now returns (*Session, *ParseStats, error).
ParseStats tracks TotalLines, SkippedLines, OrphanedToolCalls, and
Warnings (line numbers + previews for bad JSON, orphaned tool IDs,
truncated final line detection). All call sites updated.
Phase 2: New analytics.go with Analyse() and FormatAnalytics().
SessionAnalytics computes Duration, ActiveTime, ToolCounts, ErrorCounts,
SuccessRate, AvgLatency, MaxLatency, and token estimation.
Co-Authored-By: Virgil <virgil@lethean.io>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
