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-font/src/deferred_face.rs

@@ -7,9 +7,13 @@
 //!
 //! Port of `font/DeferredFace.zig` (fontconfig variant only).
 
-use crate::face::{self, Options, Variation};
-use crate::fontconfig as fc;
-use crate::{Face, Library, Presentation};
+use crate::{
+    Face,
+    Library,
+    Presentation,
+    face::{self, Options, Variation},
+    fontconfig as fc,
+};
 
 #[derive(Debug, thiserror::Error)]
 pub enum LoadError {