This PR adds support for specifyinglineHeight using pixel values with the 'px' suffix, while maintaining full backward compatibility with existing numeric multiplier format.

Problem

Previously, users could only specifylineHeight as a numeric multiplier (e.g.,1.2). When using DOM rendering, users wanted to set exact pixel values but had to manually calculate the multiplier:

// Before: Want 23px line height with 16px character height// Had to calculate: 23 ÷ 16 = 1.4375constterm=newTerminal({lineHeight:1.4375});

This was unintuitive and error-prone, especially when the character height changed.

Solution

NowlineHeight accepts both formats:

// Existing numeric format (unchanged)constterm1=newTerminal({lineHeight:1.2});// New px formatconstterm2=newTerminal({lineHeight:'24px'});

Implementation

• Type System: Updated public and headless APIs to acceptlineHeight?: number | string
• Validation: EnhancedOptionsService to validate both formats with proper error handling
• Renderers: Added sharedcalculateLineHeightInPixels() utility function for both DOM and WebGL renderers
• Safety: Enforces minimum values (≥1 for numeric, ≥1px for string, but also ≥ character height)
• WebGL Compatibility: Maintains char atlas compatibility by converting px values to multipliers when needed

Testing

• All existing tests pass (2242 passing)
• Added comprehensive test coverage for new functionality
• Validates both valid and invalid inputs
• Tests calculation logic for edge cases

Examples

// Numeric multipliers (existing behavior)newTerminal({lineHeight:1.0});// 16px char → 16px line heightnewTerminal({lineHeight:1.2});// 16px char → 19px line heightnewTerminal({lineHeight:1.5});// 16px char → 24px line height// Pixel values (new feature)newTerminal({lineHeight:'20px'});// Always 20px line heightnewTerminal({lineHeight:'23px'});// Always 23px line heightnewTerminal({lineHeight:'25px'});// Always 25px line height// Minimum enforcementnewTerminal({lineHeight:'10px'});// 16px char → 16px line height (minimum)

Fixes#2612.

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