fix(chezmoi): handle .chezmoiroot in source_dir_path

Add support for .chezmoiroot to configure source directory.## Problem

  When users have a .chezmoiroot file in their chezmoi source directory, the current chezmoi#source_dir_path setting doesn't include the root subdirectory. This causes chezmoi.vim's filetype detection to fail for files in .chezmoiscripts/ and other special directories.

  For example, with .chezmoiroot containing home:
  - Current: ~/.local/share/chezmoi
  - Expected: ~/.local/share/chezmoi/home

  ## Solution

  Read .chezmoiroot file if it exists and append its content to the source path, matching chezmoi.vim's built-in detection behavior.

  ## Testing

  Verified with:
  - .chezmoiscripts/run_once_before_*.sh.tmpl → sh.chezmoitmpl 
  - dot_config/fish/config.fish.tmpl → fish.chezmoitmpl

lua/lazyvim/plugins/extras/util/chezmoi.lua

@@ -55,7 +55,18 @@ return {
     "alker0/chezmoi.vim",
     init = function()
       vim.g["chezmoi#use_tmp_buffer"] = 1
-      vim.g["chezmoi#source_dir_path"] = vim.env.HOME .. "/.local/share/chezmoi"
+      -- Handle .chezmoiroot for users who organize source files in subdirectories
+      local source = vim.env.HOME .. "/.local/share/chezmoi"
+      local root_file = source .. "/.chezmoiroot"
+      local f = io.open(root_file, "r")
+      if f then
+        local root = f:read("*l")
+        f:close()
+        if root and root ~= "" then
+          source = source .. "/" .. vim.trim(root)
+        end
+      end
+      vim.g["chezmoi#source_dir_path"] = source
     end,
   },
   {