Problem: Command inputs and parsed modifiers have different optional
fields, and completion window IDs are annotated as floating-point
values.

Solution: Separate modifier input and return types, correct integer IDs,
and update the metadata generators and their output.

AI-assisted

Problem: Autocmd callbacks currently have to rely on curwin, which may
already have changed by the time they run. This is especially noticeable
for WinNew, WinClosed, WinResized and WinScrolled.

Solution: Track the window in the autocmd context and expose it as ev.win.
Pass it explicitly for the window events that need it.

Problem: a font set via nvim_set_hl is lost or corrupted with font-only groups,
attribute combining, and update=true, and is dropped on any attr-table rebuild.
nvim__inspect_cell also frees the font name while a returned dict still borrows it.

Solution: register font-only groups, carry font through hl_combine_attr, inherit
it on update, and persist sg_font so a rebuild can restore it. Keep interned font
names across a rebuild instead of clearing them. Add the missing font field to
get_hl_info.

Co-authored-by: Ryan Patterson <cgamesplay@cgamesplay.com>

Problem:
2d795face6e4 added support for tab-local options ('cmdheight')
to `nvim_get_option_value`, but not to:

    nvim_get_option_info2()
    nvim_set_option_value(…, { tab = … })
    gettabwinvar()

Solution:
- Update `options.lua` to model tab-local options. Introduce `kOptScopeTab`.
- Handle tab scope in the options layer so it works for all options APIs.

Note:
- No change to `gettabvar()`. Not sure if needed/wanted.

fix https://github.com/neovim/neovim/issues/31140

Problem:
Can't get a command's description from nvim_get_commands when
cmd is string.

Solution:
Returns "desc" field in nvim_get_commands.
`definition` is now empty when cmd is function type.

Problem:
Cannot remove a `@conceal` highlight when defined in highlights.scm.

Solution:
Support a `@noconceal` highlight that works similarly to `@nospell` where it
overrides the conceal set on the range to remove it. Additionally, can
set the conceal metadata field to false for the same behavior.

Problem: fg_indexed/bg_indexed were dropped from nvim_get_hl output due
to a wrong short_keys guard. HL_FG_INDEXED also wasn't cleared in
hl_blend_attrs, and HLATTRS_DICT_SIZE was too small.

Solution: Remove the short_keys guard, clear HL_FG_INDEXED in
hl_blend_attrs, bump HLATTRS_DICT_SIZE to 24, and clarify docs that
these flags mean rgb is an approximation of the cterm palette index.

Problem:
Too much boilerplate needed to use Lua to impl an excmd or f_xx
function.

Solution:
- Add `nlua_call_vimfn` which takes the args typval, executes
  Lua, and returns a typval.
- refactor(excmd): lua impl for :log, :lsp

Problem:
- Not obvious which _meta/ are generated and which should be edited
  manually.
- The require guard (`error('Cannot require a meta file')`) is not
  consistently present in all meta files.

Solution:
- Update headers.
- Add require() guard to all meta files.
- Rename generated meta files with `.gen.lua`.