[lucas-santos-f]

Fixes #1663

Only the three-point form of Sketch.arc had a docstring, so the center/radius form shows up in the class reference with no hint of what a and da mean. This adds a docstring to each overload, the way Face.normalAt does it; the multimethod Sphinx extension joins them under a single entry since #1123. The first line stays the generic "Construct an arc.", since that's the summary in the API reference table (see #1088).

• arc(p1, p2, p3): starts at p1, passes through p2, ends at p3
• arc(p2, p3): same, starting at the end of the last edge
• arc(c, r, a, da): a is the start angle in degrees from the x axis, da the angle spanned, counter-clockwise if positive; abs(da) >= 360 gives a full circle

Docstrings only, no code change. Checked locally (Linux, Python 3.13, pip install with cadquery-ocp 8.0.1.1):

• docs build with Sphinx 9.1.0: same 12 warnings as master, none new; the text shows up under Sketch.arc in the class reference
• black . --diff --check (cq fork): nothing to reformat
• pytest -n 8 tests: 900 passed, 3 skipped (two gui tests that only run on Windows, one always skipped)
• mypy cadquery: same 10 errors as master, all in occ_impl/solver.py (pip casadi)

Not touched here: for abs(da) >= 360 both a and the sign of da are ignored, since Edge.makeCircle builds a full circle without angle1/orientation. So arc((0, 0), 1, 90, 360) starts at (1, 0). I kept the docstring to "a full circle is made" for that case.

AI disclosure: this change was written with the help of Claude Code (Claude Opus 5.5). Happy to adjust anything if needed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.81%. Comparing base (8178185) to head (3f32f76).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2120   +/-   ##
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  Coverage   95.81%   95.81%           
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  Files          30       30           
  Lines        9605     9605           
  Branches     1443     1443           
=======================================
  Hits         9203     9203           
  Misses        247      247           
  Partials      155      155           

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