build: remove presubmit dependency on luvit-meta

As discussed in https://github.com/yetone/avante.nvim/pull/2536 the
project should either use luv bindings from luals or luvit-meta
library, but not both, as they conflict with each other (especially
with uv.uv_timer_t). Given that other projects such as kickstart.nvim
and lazydev.nvim are switching to use the former, we should do the same
and drop luvit-meta dependency.

Also adjust code that was using luvit-meta's annotations for timers.

lua/avante/ui/prompt_input.lua

@@ -15,7 +15,7 @@ local Utils = require("avante.utils")
 ---@field close_on_submit boolean
 ---@field spinner_chars table
 ---@field spinner_index integer
----@field spinner_timer uv_timer_t | nil
+---@field spinner_timer uv.uv_timer_t | nil
 ---@field spinner_active boolean
 ---@field default_value string | nil
 ---@field popup_hint_id integer | nil