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-onig/src/lib.rs

@@ -26,9 +26,10 @@ pub fn set_retry_limit_in_search(param: &mut MatchParam, limit: u32) {
 #[cfg(test)]
 mod tests {
     #![allow(clippy::unwrap_used)]
-    use super::*;
     use onig::{Regex, SearchOptions};
 
+    use super::*;
+
     fn search(re: &Regex, text: &str, limit: Option<u32>) -> Result<Option<usize>, onig::Error> {
         let mut param = MatchParam::default();
         if let Some(l) = limit {