feat: add command polygon & ellipse and refine command spline & rect

[mlightcad]

Summary

This PR introduces ELLIPSE and POLYGON commands and significantly enhances interactive command input flows across drawing commands.

What Changed

• Added new commands:
  • ELLIPSE (axis/center workflows, arc mode, rotation option, dynamic preview)
  • POLYGON (center mode with inscribed/circumscribed options, edge mode)
• Upgraded existing commands:
  • CIRCLE: supports center/radius, center/diameter, 2P, and 3P flows
  • RECT: supports chamfer, fillet, width, elevation, thickness, area, dimensions, and rotation
  • LINE: supports chained input with Undo and Close
  • SPLINE: supports fit/CV methods, degree/knots options, undo/close, and improved preview stability
• Input system updates:
  • Added base-angle support for angle prompts and rubber-band rendering
  • Improved keyboard handling during text input/IME composition
  • Added integer prompt support through editor APIs
• Localization:
  • Added/updated EN and ZH command and jig strings for new workflows
• Registration:
  • Registered ellipse and polygon commands in command manager/export index

Developer Notes

• getKeywords now returns AcEdPromptResult (status + optional stringResult) instead of a raw string.
• Cancel behavior for keyword prompts is now status-based rather than exception-driven.

Documentation

• Added detailed TypeDoc comments to previously unannotated classes/members in input UI modules.