* Add Version 3-L configurations and update documentation (AGENTS.md, README.md).
* Solve OpenType GSUB offset overflows and compiler bottlenecks:
- Combine SetByte lookups per character instead of position/character, reducing the total lookup count from 5,300 to 510.
- Implement useExtension on helper and scan lookups to bypass the 16-bit offset constraints.
- Use class-to-class substitutions for XOR and NoOp lookups.
* Split CloseQR into CloseQR and CloseQR_CountTail to prevent shaper offset mismatches from Multiple Substitutions.
* Remove legacy reference.html output from the build and Makefile packaging.
* Update demo.html style and font selectors to support loading and displaying the 3L font with character limit labeling.
* Keep glyph names in setupPost() to ensure shape_debug.py outputs readable glyph names.
