[BUG] Incorrect diff colouring positioning when snacks_picker_list open

[albrtyng]

Bug Description

Seems like snacks_list_picker is not being filtered out of the main window checks when a file is opened to display a diff.

To Reproduce

Steps to reproduce the behavior:

1. Open nvim
2. Toggle snacks file explorer
3. Initiate a diff with claudecode.nvim on an unopened file
4. See incorrect colouring placement

Expected Behavior

Diff colouring should be applied to the buffer containing the previous file state

Environment

• Neovim version: 0.11.6
• Claude Code CLI version: 2.1.50
• OS: macOS 26.2
• Plugin version: 0.3.0

Error Messages

N/A

Additional Context