FEAT: Initialize triangle from dict.

[genedan]

Enables the initialization of a triangle via data supplied in a dictionary. Closes #701.

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Note

Low Risk
Low risk: change is limited to accepting dict input by converting it to a pandas DataFrame, plus a unit test to confirm parity with existing DataFrame initialization.

Overview
Triangle now accepts a Python dict for the data argument by converting it to a pandas DataFrame during initialization.

Adds a regression test (test_triangle_init_from_dict) asserting a dict-backed triangle is equal to one built from an equivalent DataFrame, and updates the constructor docstring/type hints accordingly.

^{Reviewed by Cursor Bugbot for commit 1b0a7a8. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.13%. Comparing base (6cb4aab) to head (1b0a7a8).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #706   +/-   ##
=======================================
  Coverage   85.12%   85.13%           
=======================================
  Files          85       85           
  Lines        4909     4911    +2     
  Branches      629      630    +1     
=======================================
+ Hits         4179     4181    +2     
  Misses        521      521           
  Partials      209      209           

Flag	Coverage Δ
unittests	85.13% <100.00%> (+<0.01%)	⬆️

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[kennethshsu]

You are so fast @genedan, I was just about to work on this one😅