- Add passthru parameter to makeWrapper for custom attributes
- Convert mutt to use passthru instead of manual attribute merging
- This simplifies the code and makes wrapper configuration cleaner

Replace writeShellApplication with makeWrapper:
- Set NOTMUCH_CONFIG environment variable directly
- Pass muttrc via -F flag
- Remove obsolete mutt.sh script

Replace writeShellApplication with makeWrapper using flagSeparator="="
to generate the --flag=value format that mpv requires

Add flagSeparator parameter to control flag format:
- " " for "--flag value" (default, backward compatible)
- "=" for "--flag=value" format

Better formatting for attribute inheritance

Use Claude CLI's native mcp add command instead of desktop config file.
This ensures MCP servers are properly registered and store paths stay current.