Document edge case behavior and add tests for smoothing small polygons

[Copilot]

Rebased onto latest polygon branch (PR #99)

Successfully rebased this PR onto the latest commits from the polygon branch. Fixed issues that arose during rebase:

• Rebased onto origin/polygon (commits c7e3318, ebaccad, 3154eac)
• Fixed missing logger import (was removed in base branch but still used in code)
• Updated test_init_invalid_dimensions_raises to match new transpose behavior
• All 24 tests passing

Changes in this PR

• Enhanced documentation for _construct_smoothing_matrix explaining edge case behavior
• Added 3 new tests for edge cases (2-point open/closed, 3-point open polygons)
• Fixed logger import issue introduced during rebase
• Updated invalid dimension test to match new transpose logic from base branch

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[codecov]

Codecov Report

❌ Patch coverage is 54.54545% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 44.49%. Comparing base (44032aa) to head (8a19940).
⚠️ Report is 12 commits behind head on polygon.

Files with missing lines	Patch %	Lines
lapy/polygon.py	54.54%	7 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           polygon     #100      +/-   ##
===========================================
- Coverage    44.81%   44.49%   -0.32%     
===========================================
  Files           15       15              
  Lines         2727     2744      +17     
  Branches       340      348       +8     
===========================================
- Hits          1222     1221       -1     
- Misses        1391     1401      +10     
- Partials       114      122       +8     

Flag	Coverage Δ
unittests	44.49% <54.54%> (-0.32%)	⬇️

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[m-reuter]

@copilot rebase

[Copilot]

@copilot rebase

Rebased successfully onto the latest polygon branch (commit 8a19940). Fixed a logger import issue and updated a test to match the new transpose behavior from the base branch. All 24 tests passing.