add initial commit for routing engine

[ljwolf]

This adds the initial routing engine explained in #464.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 354 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.2%. Comparing base (13ca45e) to head (8b11450).
⚠️ Report is 29 commits behind head on main.

Files with missing lines	Patch %	Lines
spopt/route/utils.py	0.0%	149 Missing ⚠️
spopt/route/heuristic.py	0.0%	147 Missing ⚠️
spopt/route/engine.py	0.0%	58 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #465     +/-   ##
=======================================
- Coverage   77.8%   70.2%   -7.6%     
=======================================
  Files         27      32      +5     
  Lines       2638    4054   +1416     
=======================================
+ Hits        2053    2846    +793     
- Misses       585    1208    +623     

Files with missing lines	Coverage Δ
spopt/route/engine.py	0.0% <0.0%> (ø)
spopt/route/heuristic.py	0.0% <0.0%> (ø)
spopt/route/utils.py	0.0% <0.0%> (ø)

... and 5 files with indirect coverage changes

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[jGaboardi]

A couple thoughts from the notebook before getting into code itself

• notebook refers to spopt.Route
  • Is that meant to be referring to route.heuristic.LastMile?
  • Should we keep LastMile or consider renaming to Route?
  • Or other ideas?
• need to remove hardcoded pathing -- dylan/projects/gsoc2025