ImGui upgrade + full EzyCad GUI integration, Lua/TextEditor console, optional embedded Python console (native), and wasm HiDPI/font fixes

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High-level themes

1. Dear ImGui upgrade — Substantial update across third_party/imgui/* (version file, backends, core). Review risk: API/behavior changes, font/layout, input.
2. EzyCad + ImGui integration — main.cpp drives full GUI flow (init, render, settings save on exit, GLFW callback chaining, wasm vs native font paths).
3. HiDPI / Emscripten — Content scale, font loading without double-scaling, imgui_impl_glfw canvas/DPR-related behavior; web/EzyCad.html tweaks.
4. Lua script console — ImGuiColorTextEdit for .lua tabs; monospace console font (Cousine) where applied; menu/shortcuts for script console visibility.
5. Python console (native) — Optional embedded CPython via pybind11, Python_console, cmake/EzyCadPython.cmake, res/scripts/python/basic.py, CMake copy of Python DLL on Windows.
6. Settings / UX — GUI pane persistence includes Python console visibility; log messages for settings load/save (see gui.cpp history in diff).
7. Misc — occt_view.cpp small wasm-related tweak; main_orig.cpp stub; .gitignore entries.

Files changed (excluding vendored ImGui)

These are the application / build files that typically matter most in review:

Path	Role
CMakeLists.txt	Python optional embed, pybind11 FetchContent, font/preload/copy steps, link targets
cmake/EzyCadPython.cmake	Windows-friendly Python dev lib / DLL resolution for embedding
src/main.cpp	Window creation, scaling, fonts (DroidSans + Cousine), ImGui backends, GUI lifecycle, input chaining
src/gui.cpp, src/gui.h	Menus, panes, script/Python console toggles, settings JSON fields
src/lua_console.cpp, src/lua_console.h	Lua REPL + script tabs (TextEditor), monospace font usage
src/python_console.cpp, src/python_console.h	Python REPL + ezycad_native bindings + script tabs
res/scripts/python/basic.py	Sample Python script shipped under res/scripts/python
web/EzyCad.html	Wasm shell / layout
src/occt_view.cpp	Minor platform-specific rendering note
src/main_orig.cpp	Stub / pointer to history
.gitignore	Ignore rules

Vendored subtree (large diff): third_party/imgui/** — treat as upstream ImGui import; validate against your expected ImGui version in third_party/imgui/IMGUI_VERSION.txt.

Python console (build & runtime)

• CMake option: EZYCAD_ENABLE_PYTHON (ON by default for non-Emscripten builds in this branch).
• Requires: Python 3 development headers/libs discoverable by find_package(Python3 COMPONENTS Development).
• Not for wasm: Embedding CPython like this is native-only; Emscripten path should still build without Python.
• Windows: Post-build can copy python3xx.dll next to EzyCad.exe when resolved (see EzyCadPython.cmake).

Suggested review checklist

• ImGui regression pass — docking-free layout, fonts, widgets, file dialogs, log window.
• Native — Debug/Release, Python ON/OFF (-DEZYCAD_ENABLE_PYTHON=OFF), missing Python dev kit → clean disable message.
• Wasm — Canvas size, mouse/keyboard, fonts, Lua console (no Python).
• Settings — ezycad_settings.json round-trip; new keys (show_python_console, etc.) don’t break older files.
• Consoles — Lua + Python bindings (ezy, view, shape wrappers), script tab save/load paths under res/scripts/*.

Follow-ups (optional)

• Squash commits and replace “WIP” messages with a single conventional summary.
• Document Python embedding prerequisites in README.md (if you want users to build with Python by default).
• Add CI matrix: build with EZYCAD_ENABLE_PYTHON=OFF to avoid hard dependency on Python dev packages.