Refactor heuristics : Improve heuristic hand gestures and add on-screen HUD sample

[Aki-07]

Fixes #27

1. Refined the pinch and fist gesture detection to reduce false positives by penalizing open support fingers and rewarding proper thumb wrapping.
2. Enhanced intent detection for open-palm, point, spread, and thumbs-up gestures by incorporating palm orientation, thumb tucking, and directional weighting.
3. Added a HUD overlay displaying active gestures per hand with confidence levels for easier validation

[Aki-07]

@ruofeidu requesting for review

[ruofeidu]

LGTM.

BTW, templates are meant to be minimized, easy-to-comprehend code instead of a full sample or advanced demos. Would you move your demo to samples/ or demos/?

The HUD was part of our original design but removed due to bandwidth, thanks for adding one.

Also try adding pictures / GIFs to your demo / samples submission the next time!

[Aki-07]

@ruofeidu have addressed your comment.. sure the next time I ll try adding some demos