style: apply nightly rustfmt import grouping across the workspace

rustfmt.toml sets group_imports, imports_granularity and imports_layout,
which are nightly-only; agents formatted with stable rustfmt, which
ignored them. This is a formatting-only pass with `cargo +nightly fmt`.

Test Plan:
- cargo clippy --workspace --all-targets -- -D warnings
- cargo test --workspace

crates/ghostty-cli/src/help.rs

@@ -4,8 +4,7 @@ use std::io::Write;
 
 use ghostty_config::config_struct;
 
-use crate::error::Error;
-use crate::ghostty::Action;
+use crate::{error::Error, ghostty::Action};
 
 config_struct! {
     // Note that this options struct doesn't implement the `help` decl like other