Add Lua/Python bindings for programmatic sketch creation

[trailcode]

Summary

• Add view.add_sketch, view.add_edge, and view.finish_sketch_edges bindings to both Lua and Python consoles, backed by new thin Occt_view / Sketch wrappers.
• Add Lua sketch inspection bindings (curr_sketch_node*, curr_sketch_dim*) for parity with Python.
• Update sierpinski.py and add sierpinski.lua with create_sierpinski_sketch() demo helpers.
• Document the new APIs in docs/scripting.md and src/doc/script.md.
• Remove unused ui_font.h (font size constant inlined in main.cpp).

Closes #169

Test plan

• Build desktop with Python enabled; open View -> Python Console
• Run ezy.help() and confirm sketch create/read APIs are listed
• Run create_sierpinski_sketch(3, 20.0) in Python; verify a new sketch with edges appears
• Open View -> Lua Console; run create_sierpinski_sketch(3, 20.0); verify same result
• Confirm view.curr_sketch_node_count() / view.curr_sketch_node(i) return expected coordinates after sketch creation

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