mappings: add ft option for filetype-scoped keymaps

[theol-git]

Aim

Adds an ft option to vim.keymaps, so a keymap can be scoped to specific
filetypes while keeping the configuration declarative inside vim.keymaps.

Today vim.keymaps only emits global mappings. With ft, nvf instead generates
a FileType autocmd that creates a buffer-local mapping whenever a buffer of one
of the given filetypes is opened. ft defaults to an empty list, which keeps the
mapping global. This is not lazy loading — it only makes keymaps active for
specific filetypes.

Example:

vim.keymaps = [
  {
    mode = "n";
    key = "<leader>p";
    action = "<cmd>Git push<CR>";
    desc = "Push commit";
    ft = [ "fugitive" ];
  }
];

generates:

vim.api.nvim_create_autocmd("FileType", {
  pattern = { "fugitive" },
  callback = function()
    vim.keymap.set("n", "<leader>p", "<cmd>Git push<CR>", {
      buffer = true,
      desc = "Push commit",
    })
  end,
})

Testing

• Verified the generated Lua through module evaluation
  (config.vim.builtLuaConfigRC) for global, ft = [...], and ft = [] cases.
• Tested in a real nvf build using a filetype-scoped keymap; confirmed the buffer-local mapping appears only on buffers of the matching filetype.
• Built .#nix, .#maximal, and .#docs-html successfully.

Sanity Checking

• I have updated the changelog as per my changes
• I have tested, and self-reviewed my code
• My changes fit guidelines found in hacking nvf
• Style and consistency
  • I ran Alejandra to format my code (nix fmt)
  • My code conforms to the editorconfig configuration of the project
  • My changes are consistent with the rest of the codebase
• If new changes are particularly complex:
  • [N/A] My code includes comments in particularly complex areas
  • I have added a section in the manual
  • [N/A] (For breaking changes) I have included a migration guide
• Package(s) built:
  • .#nix (default package)
  • .#maximal
  • .#docs-html (manual, must build)
  • [N/A] .#docs-linkcheck (optional, please build if adding links)
• Tested on platform(s)
  • x86_64-linux
  • [] aarch64-linux
  • [] x86_64-darwin
  • [] aarch64-darwin

[github-actions]

🚀 Live preview deployed from 5e4f212

View it here:

Debug Information

Triggered by: theol-git

HEAD at: feature/filetype-keymaps

Reruns: 4049