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-vt/src/sgr.rs

@@ -4,8 +4,10 @@
 //! C-ABI helpers of the Zig version (`Attribute.C`, `cval`, `lib.Enum`
 //! `Tag`) are intentionally not ported.
 
-use crate::color::{Name, Rgb};
-use crate::parser::{MAX_PARAMS, SepList};
+use crate::{
+    color::{Name, Rgb},
+    parser::{MAX_PARAMS, SepList},
+};
 
 /// Attribute type for SGR
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -413,9 +415,10 @@ impl<'a> Iterator for Parser<'a> {
 mod tests {
     #![allow(clippy::unwrap_used)]
 
-    use super::*;
     use Attribute as A;
 
+    use super::*;
+
     fn rgb(r: u8, g: u8, b: u8) -> Rgb {
         Rgb { r, g, b }
     }