Implement acute angle detection for orthogonal link labels with AutoRight/AutoLeft

[ugwis]

Summary

This PR implements acute angle detection for orthogonal link labels to improve visual clarity by positioning labels on the acute angle side of the longest horizontal segment.

Changes

Core Implementation

• Vector.Cross(): Add 2D cross product calculation method for angle detection
• findPerpendicularSegments(): Detect 90-degree angles using normalized cross product
• getAcuteAngleSide(): Independent Left/Right acute angle detection for each label

Label Positioning Logic

• Acute angle detection: Use cross product sign to determine rotation direction
  • crossProduct > 0: Right side acute (90° counterclockwise)
  • crossProduct < 0: Left side acute (90° clockwise, 270° counterclockwise)
• Parameter reversal: When acute angles detected, reverse all placement parameters:
  • source/target, autoPt1/autoPt2, Left/Right positioning, autoPos direction
  • Use (autoPos + 8) mod 16 for 180-degree autoPos rotation

New Label Types

• AutoRight/AutoLeft: Replace Right/Left with more explicit auto-positioning labels
• Backward compatibility: Maintains existing SourceRight/SourceLeft/TargetRight/TargetLeft

Testing

• Comprehensive tests: Added tests for autoPos reversal and acute angle detection
• Integration tests: YAML-based tests with various orthogonal link configurations
• Fixed existing tests: Updated expectations for correct cross product calculations

Visual Impact

Labels are now positioned on the acute angle side of orthogonal links, providing:

• Better visual clarity by avoiding overlap with link paths
• Consistent label placement near acute angle control points
• Improved readability for complex orthogonal diagrams

Example Usage

Diagram:

  Links:
    # Test case 1: Source to Target1 - should create L-shaped path
    - Source: SourceResource
      Target: TargetResource1
      Type: orthogonal
      Labels:
        AutoRight:
          Title: "R1"
        AutoLeft:
          Title: "L1"

    # Test case 2: Source to Target2 - should create different L-shaped path
    - Source: SourceResource
      Target: TargetResource2
      Type: orthogonal
      Labels:
        AutoRight:
          Title: "R2"
        AutoLeft:
          Title: "L2"

Labels will automatically position themselves on the appropriate side based on acute angle detection.