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-apprt-gtk/src/class/inspector_window.rs

@@ -2,13 +2,10 @@
 //!
 //! Window for displaying the Ghostty inspector.
 
-use adw::prelude::*;
-use adw::subclass::prelude::*;
+use adw::{prelude::*, subclass::prelude::*};
 use gtk::glib;
 
-use super::debug_warning::DebugWarning;
-use super::inspector_widget::InspectorWidget;
-use super::surface::Surface;
+use super::{debug_warning::DebugWarning, inspector_widget::InspectorWidget, surface::Surface};
 
 glib::wrapper! {
     pub struct InspectorWindow(ObjectSubclass<imp::InspectorWindow>)