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-config/src/url.rs

@@ -116,9 +116,10 @@ pub const REGEX: &str = concatcp!(
 #[cfg(test)]
 #[allow(clippy::unwrap_used)]
 mod tests {
-    use super::*;
     use onig::Regex;
 
+    use super::*;
+
     #[test]
     fn url_regex() {
         let re = Regex::new(REGEX).unwrap();