feat(viewer): add AutoCAD-style command-line point and mixed prompt input

[mlightcad]

Summary

• Add \parseCommandLine\ to input handlers with \AcEdPointInputContext\ for reference/cursor-aware point parsing (absolute/relative Cartesian, polar, rubber-band distance)
• Introduce \AcEdPromptInputSession\ to unify command-line keyword and typed input with AutoCAD-style precedence (geometric before keywords; strings try keywords first)
• Route floating prompts and scripted input through the same parsing path; show localized invalid-input feedback on the command line

Test plan

• 
  pm test -- --testPathPatterns=AcEdPointHandler|AcEdPromptInputSession\ (9 tests)
• 
  px tsc --noEmit\ in \packages/cad-simple-viewer`n- [ ] Manually pick a point prompt with keywords and verify \50,30\ resolves as coordinates while \C\ resolves as keyword
• Verify relative (@10,5) and polar (\10<90) point entry during interactive prompts

Made with Cursor