feat: add ftxui 6.1.9 (C++ TUI library) (#9)

Pure compiled C++ library (no C++23 modules); uses mcpp 0.0.4's new
glob exclusion syntax to skip the ~46 *_test.cpp / *_fuzzer.cpp files
that live alongside the library sources:

    sources = {
        "*/src/ftxui/**/*.cpp",
        "!*/src/ftxui/**/*_test.cpp",
        "!*/src/ftxui/**/*_fuzzer.cpp",
    }

Produces a single `libftxui.a` covering screen + dom + component.
Public headers exposed via `include_dirs = { "*/include" }`.

Tarball: https://github.com/ArthurSonzogni/FTXUI/archive/refs/tags/v6.1.9.tar.gz
SHA256:  45819c1e54914783d4a1ca5633885035d74146778a1f74e1213cdb7b76340e71

Author: Sunrisepeak

pkgs/f/ftxui.lua

@@ -0,0 +1,54 @@
+-- M6.x glob-aware Form B descriptor for FTXUI 6.1.9.
+--
+-- Pure C++ library (no C++23 modules); compiled sources + public headers.
+-- Uses mcpp 0.0.4's glob exclusion (`!` prefix) to skip the ~46
+-- *_test.cpp / *_fuzzer.cpp files that live alongside the library
+-- sources in the same directories.
+--
+-- Produces a single static archive `libftxui.a` covering all three
+-- upstream cmake targets (ftxui-screen, ftxui-dom, ftxui-component).
+
+package = {
+    spec        = "1",
+    name        = "ftxui",
+    description = "C++ Functional Terminal User Interface (screen + dom + component)",
+    licenses    = {"MIT"},
+    repo        = "https://github.com/ArthurSonzogni/FTXUI",
+    type        = "package",
+
+    xpm = {
+        linux = {
+            ["6.1.9"] = {
+                url    = "https://github.com/ArthurSonzogni/FTXUI/archive/refs/tags/v6.1.9.tar.gz",
+                sha256 = "45819c1e54914783d4a1ca5633885035d74146778a1f74e1213cdb7b76340e71",
+            },
+        },
+        macosx = {
+            ["6.1.9"] = {
+                url    = "https://github.com/ArthurSonzogni/FTXUI/archive/refs/tags/v6.1.9.tar.gz",
+                sha256 = "45819c1e54914783d4a1ca5633885035d74146778a1f74e1213cdb7b76340e71",
+            },
+        },
+        windows = {
+            ["6.1.9"] = {
+                url    = "https://github.com/ArthurSonzogni/FTXUI/archive/refs/tags/v6.1.9.tar.gz",
+                sha256 = "45819c1e54914783d4a1ca5633885035d74146778a1f74e1213cdb7b76340e71",
+            },
+        },
+    },
+
+    -- Form B `mcpp` segment: paths are globs relative to the verdir.
+    -- The leading `*/` absorbs the GitHub tarball's `FTXUI-6.1.9/` wrap.
+    mcpp = {
+        language     = "c++23",
+        import_std   = false,          -- pure compiled lib, no `import std;`
+        include_dirs = { "*/include" },
+        sources = {
+            "*/src/ftxui/**/*.cpp",
+            "!*/src/ftxui/**/*_test.cpp",      -- 30+ gtest files
+            "!*/src/ftxui/**/*_fuzzer.cpp",     -- ~16 fuzz targets
+        },
+        targets = { ["ftxui"] = { kind = "lib" } },
+        deps    = { },
+    },
+}