Add interactive time-based filtering and animations

[mgsrevolver]

Hi there. This is my first ever pull request, so please feel free to ignore or trash it, I'm learning as I go.

Summary

Added time-based filtering capabilities to the location history heatmap with animations and custom date range selection.

Features Added

• Three time filter modes:

  • Static (all data - default)
  • Date Range (custom date selection with optional drill-down)
  • Animation (auto-play through time periods)

• Custom date range selector with month/year dropdowns

• Smooth blend transitions between time periods (configurable)

• Animation controls: play/pause, step forward/back, loop, adjustable speed

• Time grouping: monthly or yearly views

• Timestamp extraction from all Google Takeout formats with interpolation (approximated)

Configuration

New defaults optimized to my taste, but can be disregarded:

• Radius: 11
• Blur: 6
• Max Intensity: 4.0
• Animation speed: 100ms with smooth transitions enabled

Testing

Tested with 50K+ location points across multiple years.