Fix ConvexHull to return points in counter-clockwise order

[Microindole]

Description

Fixes the convexHullRecursive method to return points in counter-clockwise (CCW) order, resolving issues with downstream geometric algorithms.

Problem

The original implementation used HashSet to collect hull points, which doesn't preserve order. This caused:

• Incorrect results in algorithms like Rotating Calipers
• Test failures expecting ordered output
• Unpredictable geometric computations

Solution

• Added sortCounterClockwise() method to sort points in CCW order
• Start from the bottom-most, left-most point for deterministic results
• Added distanceSquared() helper to handle collinear points correctly
• Enhanced tests with isCounterClockwise() verification

Changes

Modified Files

• ConvexHull.java: Added CCW sorting logic
• ConvexHullTest.java: Added CCW order verification tests

Key Methods Added

• sortCounterClockwise(): Sorts hull points in CCW order from pivot
• distanceSquared(): Computes squared distance for collinear point handling

Testing

All existing tests pass, plus new tests verify:

• Triangle with intermediate point
• Collinear points
• Complex polygon (10 points)
• Square (all corners on hull)
• Pentagon with interior point
• CCW order verification for all cases

Example

List points = Arrays.asList(
    new Point(0, 0), new Point(3, 0), 
    new Point(3, 3), new Point(0, 3)
);
List hull = ConvexHull.convexHullRecursive(points);
// Now returns: [(0,0), (3,0), (3,3), (0,3)] in CCW order

Related Issues

Fixes #6605

Checklist

• Code follows project style guidelines
• All tests pass
• Added tests for new functionality
• Documentation updated (if needed)
• No breaking changes to existing API

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.59459% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.95%. Comparing base (4a97258) to head (132653c).

Files with missing lines	Patch %	Lines
...in/java/com/thealgorithms/geometry/ConvexHull.java	94.59%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6810      +/-   ##
============================================
+ Coverage     77.93%   77.95%   +0.02%     
- Complexity     6420     6430      +10     
============================================
  Files           736      736              
  Lines         21444    21476      +32     
  Branches       4198     4204       +6     
============================================
+ Hits          16712    16742      +30     
  Misses         4061     4061              
- Partials        671      673       +2     

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