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-bench/src/args.rs

@@ -1,9 +1,11 @@
 //! Minimal `--key=value` option parsing (the subset of `cli/args.zig` used by
 //! the benchmark and synthetic CLIs).
-use std::collections::HashMap;
-use std::fs::File;
-use std::io::{self, Read};
-use std::str::FromStr;
+use std::{
+    collections::HashMap,
+    fs::File,
+    io::{self, Read},
+    str::FromStr,
+};
 
 /// Parsed `--key[=value]` arguments.
 #[derive(Debug, Default)]

crates/ghostty-bench/src/benches.rs

@@ -1,7 +1,7 @@
 //! The individual benchmarks (ports of `benchmark/*.zig`) and the CLI action
 //! dispatch (`benchmark/cli.zig`).
-use crate::args::{Args, data_file, read_short};
-use crate::benchmark::{Benchmark, BenchmarkFailed, Result, RunMode, RunResult, run};
+use std::{hint::black_box, io::Read};
+
 use ghostty_terminal::{
     point::{Coordinate, Point},
     render::RenderState,
@@ -14,8 +14,11 @@ use ghostty_vt::{
     stream::{Action, Handler, Stream},
     utf8_decoder::Utf8Decoder,
 };
-use std::hint::black_box;
-use std::io::Read;
+
+use crate::{
+    args::{Args, data_file, read_short},
+    benchmark::{Benchmark, BenchmarkFailed, Result, RunMode, RunResult, run},
+};
 
 const CHUNK: usize = 4096;
 

crates/ghostty-bench/src/bin/ghostty-synthetic.rs

@@ -1,11 +1,14 @@
 //! `ghostty-synthetic +<ascii|utf8|osc> [--option=value ...]`: endless
 //! synthetic data on stdout (port of `synthetic/main.zig`).
+use std::{
+    io::{BufWriter, Write},
+    process::ExitCode,
+};
+
 use ghostty_bench::{
     args::Args,
     synthetic::{OscStyle, Rng, run_ascii, run_osc, run_sgr, run_utf8},
 };
-use std::io::{BufWriter, Write};
-use std::process::ExitCode;
 
 fn run() -> Result<(), String> {
     let argv: Vec<String> = std::env::args().skip(1).collect();

crates/ghostty-bench/src/main.rs

@@ -1,7 +1,8 @@
 //! `ghostty-bench +<action> [--option=value ...]` (port of `main_bench.zig`).
-use ghostty_bench::{args::Args, benches};
 use std::process::ExitCode;
 
+use ghostty_bench::{args::Args, benches};
+
 fn main() -> ExitCode {
     let argv: Vec<String> = std::env::args().skip(1).collect();
     let mut action = None;

crates/ghostty-bench/src/synthetic.rs

@@ -1,8 +1,9 @@
 //! Synthetic data generators (port of `ZIG/src/synthetic`): random bytes,
 //! UTF-8 and OSC sequences, used to feed the benchmarks.
-use ghostty_vt::string_encoding::url_percent_encode;
 use std::io::{self, Write};
 
+use ghostty_vt::string_encoding::url_percent_encode;
+
 /// xoshiro256++ (what Zig's `std.Random.DefaultPrng` is).
 #[derive(Debug, Clone)]
 pub struct Rng {
@@ -666,9 +667,10 @@ fn finished(r: io::Result<usize>) -> io::Result<bool> {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use ghostty_vt::osc::Parser;
 
+    use super::*;
+
     const SEED: u64 = 0xC0FFEEEEEEEEEEEE;
 
     #[test]