Update heap

[harisankar95]

• node attributes updated
• added simple heap structure

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (868ef4d) 89.72% compared to head (9faee0c) 90.27%.

Files	Patch %	Lines
pathfinding3d/core/heap.py	95.23%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #5      +/-   ##
==========================================
+ Coverage   89.72%   90.27%   +0.54%     
==========================================
  Files          17       18       +1     
  Lines         652      699      +47     
==========================================
+ Hits          585      631      +46     
- Misses         67       68       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.