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/terminal/tests/p3.rs

@@ -1,9 +1,7 @@
+use ghostty_vt::{color::Rgb, modes::Mode, sgr::Attribute as A};
+
 use super::*;
-use crate::page::ContentTag;
-use crate::point::Tag;
-use ghostty_vt::color::Rgb;
-use ghostty_vt::modes::Mode;
-use ghostty_vt::sgr::Attribute as A;
+use crate::{page::ContentTag, point::Tag};
 
 fn cr_lf(t: &mut Terminal) {
     t.carriage_return();