Replace the busted-based Lua test runner with a repo-local harness.
The new harness runs spec files directly under `nvim -ll`, ships its own
reporter and lightweight `luassert` shim, and keeps the helper/preload
flow used by the functional and unit test suites.
Keep the file boundary model shallow and busted-like by restoring `_G`,
`package.loaded`, `package.preload`, `arg`, and the process environment
between files, without carrying extra reset APIs or custom assertion
machinery.
Update the build and test entrypoints to use the new runner, add
black-box coverage for the harness itself, and drop the bundled
busted/luacheck dependency path.
AI-assisted: Codex
Problem:
No way to detect at runtime if the build includes unibilium (or whatever
terminfo layer we swap it with later).
Solution:
Support `has('terminfo')`.
Problem:
We have too many build flags.
BUNDLED_CMAKE_FLAG is redundant with DEPS_CMAKE_FLAGS.
Solution:
In documentation, refer to DEPS_CMAKE_FLAGS instead of BUNDLED_CMAKE_FLAG.
compile time features are hot again.
Note: this changes the &term value for builtin definition from
'builtin_xterm' to just 'xterm'. It's an xterm regardless of we use an
external definition or an internal. Prior to this commit the vast
majority of POSIX users will have used external terminfo, so plugins and
scripts are only going to have checked for &term == 'xterm' or 'tmux' or
whatever.
The status of external loading is still available in "nvim -V3" output.
BUILD.md: Add git to prerequisites
The git command is literally the first one in the build instructions, therefore it's reasonable to treat it as one of the prerequisites. Void Linux already had git as one of the prerequisites; this commits adds git to all the other Unix systems.
Problem:
The default invocation would install the non-ucrt gcc package, the build would
fail now that UCRT is not supported. #22534
Solution:
Mention mingw-w64-ucrt pacman package instead.
Problem: Adding support for modern Nvim features (reflow, OSC 8, full
utf8/emoji support) requires coupling libvterm to Nvim internals
(e.g., utf8proc).
Solution: Vendor libvterm at v0.3.3.
Problem: Neovim bundles treesitter parsers for bash and python but does
not use them by default. This dilutes the messaging about the bundled
parsers being required for functionality or reasonable out-of-the-box
experience. It also increases the risk of query incompatibilities for no
gain.
Solution: Stop bundling bash and python parser and queries.
Xcode does not allow having multiple targets depend on a custom command.
This limitation severely hinders its usability and complying with it
would likely require extensive refactoring and boilerplate. It makes
more sense to simply refer users to use "Ninja" or "Unix Makefiles"
instead.
