feat: add configurable input window height for vertical layout (#773)

Co-authored-by: amojury <wujiajun880@gmail.com>

README.md

@@ -261,6 +261,7 @@ _See [config.lua#L9](./lua/avante/config.lua) for the full config_
     },
     input = {
       prefix = "> ",
+      height = 8, -- Height of the input window in vertical layout
     },
     edit = {
       border = "rounded",

lua/avante/config.lua

@@ -172,6 +172,7 @@ Respect and use existing conventions, libraries, etc that are already present in
     },
     input = {
       prefix = "> ",
+      height = 8, -- Height of the input window in vertical layout
     },
     edit = {
       border = "rounded",

lua/avante/sidebar.lua

@@ -1415,7 +1415,7 @@ function Sidebar:create_input(opts)
 
   local get_size = function()
     if self:get_layout() == "vertical" then return {
-      height = 8,
+      height = Config.windows.input.height,
     } end
 
     local selected_code_size = self:get_selected_code_size()