feat(ftxui): add 7.0.3

[FarnaHerry]

What

Adds FTXUI 7.0.3 (latest upstream release, 2026-08-06) alongside the existing 6.1.9, and bumps the core smoke member to it.

Descriptor impact

• Layout unchanged: include/ftxui + src/ftxui/{screen,dom,component,util}, so the 6.1.9 globs apply verbatim. Test/fuzzer exclusions still cover 7.0.3's 47 *_test.cpp / 6 *_fuzzer.cpp.
• Public API source-compatible for what the smoke test uses (hbox/text/separator, Dimension::Fit, Screen::Create(Dimensions, Dimensions), Render) — runtime.cpp needs no change.
• Modules deliberately NOT enabled: 7.0.3 ships upstream .cppm units, and an earlier revision of this PR compiled them (import ftxui; worked on the llvm/macos/windows legs). The linux GCC leg failed: upstream's units put libstdc++ headers textually in the global module fragment, and GCC 16 cannot consume overlapping GMFs from the four sub-module BMIs (redefinitions of std::__terminate, std::allocator, …). Upstream's own CI builds modules llvm-only (# TODO add gcc / msvc in build.yaml), so the module units stay out until upstream supports more than clang.

The one skew: loop.cpp

FTXUI 7 moved Loop's method definitions from loop.cpp into app.cpp and dropped loop.cpp from the CMake build — but the stale file still ships in the 7.0.3 tarball. Our glob compiles it, duplicating Loop::{~Loop,RunOnce,...} at the consumer's link (a dependency's objects all enter the link; no lazy archive selection). 6.1.9 has no app.cpp and genuinely needs loop.cpp, and there are no per-version build blocks yet (mcpp-community/mcpp#290).

Fix: a small install() hook (same normalisation pattern as compat.eui-neo) deletes loop.cpp only when app.cpp exists — exactly the 7.x layout — keeping 6.1.9 intact.

CN mirror

Not published to mcpp-res; plain-string GLOBAL fallback (same precedent as eui-neo 0.5.7). sha256 double-checked against the GitHub tag archive: e7c62ffe19009759821b4f0f8df7f2a6fb83784c3a9f1477d81f56d3ee723c88.

Local verification (mcpp 2026.8.29.1)

• mcpp test -p core → ok on 7.0.3 (ftxui builds, smoke assertions pass)
• mcpp test -p core re-pointed at 6.1.9 → ok through the new hook (loop.cpp kept)
• Lints: check_mirror_urls, check_package_name, check_platform_version_parity, check_duplicate_versions, check_cross_package_refs, mcpp xpkg parse — all green

[Sunrisepeak]

这里看 install hook 只是移动了目录, 好像没有其他额外功能，是不是可以省去

[FarnaHerry]

这个 hook 除了保持默认解包目录结构外，还会在检测到 7.x 的 app.cpp 时删除 tarball 中遗留的 loop.cpp。FTXUI 7.0.3 同时编译 app.cpp 和 loop.cpp 会产生 Loop::* 重复定义，而 6.1.9 仍然需要 loop.cpp。目前描述符还不能按版本声明不同的 sources（mcpp-community/mcpp#290），所以暂时需要在 install hook 中处理这个版本差异。这里的目录移动是自定义 install hook 接管默认安装流程后，为保持原有 */ glob 解包结构所需的。基于这个兼容约束，是否可以保留该 hook？我也可以进一步精简注释，让删除 loop.cpp 的目的更突出。