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/kitty/graphics_storage.rs

@@ -21,9 +21,11 @@ use std::collections::{BTreeMap, HashMap};
 use ghostty_vt::kitty::graphics_command::Delete;
 
 use super::graphics_image::{Image, LoadingImage, Rect};
-use crate::page_list::{Overflow, PageList, TrackedPin};
-use crate::point::{Coordinate, Point};
-use crate::size::CellCountInt;
+use crate::{
+    page_list::{Overflow, PageList, TrackedPin},
+    point::{Coordinate, Point},
+    size::CellCountInt,
+};
 
 /// The subset of terminal state that the storage needs to read.
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]