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-terminal/src/style.rs

@@ -1,13 +1,15 @@
 //! Cell styles, color resolution, and VT/HTML serialization.
-use crate::page::{Cell, ContentTag};
-use ghostty_vt::{
-    color::{Palette, Rgb},
-    sgr::Underline,
-};
 use std::{
     fmt,
     hash::{Hash, Hasher},
 };
+
+use ghostty_vt::{
+    color::{Palette, Rgb},
+    sgr::Underline,
+};
+
+use crate::page::{Cell, ContentTag};
 /// Nonzero page-local style identifier.
 pub type Id = u16;
 /// The default style needs no set lookup.