fix: replace vim.fn.expand with vim.fs.normalize

Using vim.fs.normalize provides better path normalization across
different operating systems. This change improves path handling
consistency in file operations for the CopilotChat plugin.

There's also a typo fix in the function name from 'normalie' to
'normalize' at one location.

Author: deathbeam

lua/CopilotChat/init.lua

@@ -785,7 +785,7 @@ function M.save(name, history_path)
   end
 
   local history = vim.json.encode(client.history)
-  history_path = vim.fn.expand(history_path)
+  history_path = vim.fs.normalize(history_path)
   vim.fn.mkdir(history_path, 'p')
   history_path = history_path .. '/' .. name .. '.json'
   local file = io.open(history_path, 'w')
@@ -814,7 +814,7 @@ function M.load(name, history_path)
     return
   end
 
-  history_path = vim.fn.expand(history_path) .. '/' .. name .. '.json'
+  history_path = vim.fs.normalize(history_path) .. '/' .. name .. '.json'
   local file = io.open(history_path, 'r')
   if not file then
     return

lua/CopilotChat/utils.lua

@@ -114,17 +114,17 @@ end
 --- Finds the path to the user's config directory
 ---@return string?
 function M.config_path()
-  local config = vim.fn.expand('$XDG_CONFIG_HOME')
+  local config = vim.fs.normalize('$XDG_CONFIG_HOME')
   if config and vim.fn.isdirectory(config) > 0 then
     return config
   end
   if vim.fn.has('win32') > 0 then
-    config = vim.fn.expand('$LOCALAPPDATA')
+    config = vim.fs.normalie('$LOCALAPPDATA')
     if not config or vim.fn.isdirectory(config) == 0 then
-      config = vim.fn.expand('$HOME/AppData/Local')
+      config = vim.fs.normalize('$HOME/AppData/Local')
     end
   else
-    config = vim.fn.expand('$HOME/.config')
+    config = vim.fs.normalize('$HOME/.config')
   end
   if config and vim.fn.isdirectory(config) > 0 then
     return config