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-termio/src/shell_integration.rs

@@ -42,8 +42,7 @@ impl Shell {
     }
 }
 
-pub use ghostty_config::command::Command;
-pub use ghostty_config::types_b::ShellIntegrationFeatures;
+pub use ghostty_config::{command::Command, types_b::ShellIntegrationFeatures};
 
 #[derive(Debug, thiserror::Error)]
 pub enum Error {