Activity Trace 0.8.0

New features: - Statistics screen with summary cards, timeline charts, top apps, breakdown - Blocked system apps auto-configured on fresh install - Diagnostic error logs for export and backup failures Improvements: - Timeline charts now same size — no jumping when switching tabs - Top apps always visible (even with 0 or 1 entry) - Breakdown always shown after timeline - More detailed export error messages Fixes: - Export no longer crashes on some Android 16 devices - SQLite backup no longer fa