fix: exclude snacks_picker_list from main editor window detection (#165)

Add snacks_picker_list filetype to the exclusion list in:
- find_main_editor_window(): prevents picker from being selected as target
- _create_diff_view_from_window(): creates split when picker is focused

This fixes diff view behavior when using snacks.nvim picker.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: tuannvm

lua/claudecode/diff.lua

@@ -73,6 +73,7 @@ local function find_main_editor_window()
         or filetype == "netrw"
         or filetype == "aerial"
         or filetype == "tagbar"
+        or filetype == "snacks_picker_list"
       )
     then
       is_suitable = false
@@ -918,7 +919,7 @@ function M._create_diff_view_from_window(
       local buftype = vim.api.nvim_buf_get_option(buf, "buftype")
       local filetype = vim.api.nvim_buf_get_option(buf, "filetype")
 
-      if buftype == "terminal" or buftype == "prompt" or filetype == "neo-tree" then
+      if buftype == "terminal" or buftype == "prompt" or filetype == "neo-tree" or filetype == "snacks_picker_list" then
         create_split()
       end