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-os/src/systemd.rs

@@ -70,7 +70,13 @@ pub fn launched_by_systemd() -> bool {
 /// variable set and these functions essentially become a no-op.
 pub mod notify {
     use rustix::net::{
-        AddressFamily, SendFlags, SocketAddrUnix, SocketFlags, SocketType, connect, send,
+        AddressFamily,
+        SendFlags,
+        SocketAddrUnix,
+        SocketFlags,
+        SocketType,
+        connect,
+        send,
         socket_with,
     };
 
@@ -168,9 +174,10 @@ pub mod notify {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use std::os::unix::net::UnixDatagram;
 
+    use super::*;
+
     #[test]
     fn not_launched_without_env() {
         temp_env::with_vars(