fix: Correct touched section index in PieChart with zero-value sections

[mahmoodhamdi]

Problem

When a PieChart has sections with zero values (e.g., [0, 0, 100, 200, 300]), touching any visible section returns the wrong touchedSectionIndex. For example, touching the section with value 100 (index 2) incorrectly returns index 0.

Root Cause

The drawSections method skips zero-value sections with continue, so they aren't drawn. However, handleTouch does not skip them — it generates a section path with a zero sweep angle, which can incorrectly match a touch point before the actual visible section is checked.

Solution

Added the same if (section.value == 0) continue; check to the handleTouch loop, matching the behavior of drawSections.

Testing

Added a unit test with sections [0, 0, 100, 200, 300] that verifies:

• Touching section with value 100 returns index 2
• Touching section with value 200 returns index 3
• Touching section with value 300 returns index 4
• Touching center returns -1

Checklist

• flutter analyze passes with zero warnings
• flutter test passes
• dart format . applied
• CHANGELOG.md updated

Closes #1632

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.92%. Comparing base (d3a8ac2) to head (d7308cb).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2067   +/-   ##
=======================================
  Coverage   92.92%   92.92%           
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  Files          50       50           
  Lines        3873     3874    +1     
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+ Hits         3599     3600    +1     
  Misses        274      274           

Flag	Coverage Δ
flutter	92.92% <100.00%> (+<0.01%)	⬆️

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[imaNNeo]

You don't need to add the changelog line in this file anymore.
We'll generate it based on the commit history from now on.

[imaNNeo]

Good catch!
It's ready to merge.
Please remove your changelog in CHANGELOG.md, and update your branch.
Then we're good to go!