docs(examples): adapt solder ball example to use create_fill_pattern

[Copilot]

Description

Replaces the manual copy+translate+subtract nested loop in the BGA solder ball example with create_fill_pattern, which stamps the entire 3×3 infill hole array in a single API call.

Source model changes:

• Add PITCH = 1.0 and SOLDER_RADIUS = 0.25 constants; remove pre-sketched seed bodies at origin
• Subtract one seed cylinder at corner (−1, −1) spanning the full infill height, then call create_fill_pattern(FillPatternType.GRID, margin=PITCH/2, x_spacing=PITCH, y_spacing=PITCH) — 27 individual subtract operations → 1 call
• Create the 9 solder cylinders + 18 copper pads with straightforward per-position extrude_sketch calls (no copy/translate)

Target model: unchanged — create_fill_pattern targets concave features in a flat host face; the revolve-based solder balls are convex and not applicable.

Please add the deploy-doc-pr label to publish and validate the rendered docs.

Issue linked

Follow-up to #2939.

Checklist

• I have tested my changes locally.
• I have added necessary documentation or updated existing documentation.
• I have followed the coding style guidelines of this project.
• I have added appropriate unit tests.
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved to the PR if any.
• I have assigned this PR to myself.
• I have added the minimum version decorator to any new backend method implemented.
• I have made sure that the title of my PR follows Conventional commits style (e.g. feat: extrude circle to cylinder)

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 0 complexity · 0 duplication

Metric	Results
Complexity	0
Duplication	0

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.89%. Comparing base (c0463f0) to head (8b5c66d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2944   +/-   ##
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  Coverage   93.89%   93.89%           
=======================================
  Files         175      175           
  Lines       15515    15515           
=======================================
  Hits        14568    14568           
  Misses        947      947           

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[github-actions]

The documentation for this pull request will be available at https://geometry.docs.pyansys.com/pull/2944. Please allow some time for the documentation to be deployed.