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-vt/src/osc/parsers/color.rs

@@ -1,8 +1,10 @@
 //! OSC color operations: 4, 5, 10-19, 104, 105, 110-119
 //! (ZIG/src/terminal/osc/parsers/color.zig).
 
-use crate::color::{Dynamic as DynamicColor, Rgb, Special as SpecialColor};
-use crate::osc::{Command, Parser, State, Terminator};
+use crate::{
+    color::{Dynamic as DynamicColor, Rgb, Special as SpecialColor},
+    osc::{Command, Parser, State, Terminator},
+};
 
 /// The possible operations we support for colors.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]

crates/ghostty-vt/src/osc/parsers/kitty_color.rs

@@ -1,8 +1,10 @@
 //! OSC 21, the Kitty Color Protocol (ZIG/src/terminal/osc/parsers/kitty_color.zig).
 
-use crate::color::Rgb;
-use crate::kitty::color::{Kind, OSC, Request};
-use crate::osc::{Command, Parser, State, Terminator};
+use crate::{
+    color::Rgb,
+    kitty::color::{Kind, OSC, Request},
+    osc::{Command, Parser, State, Terminator},
+};
 
 /// Parse OSC 21, the Kitty Color Protocol.
 pub fn parse(parser: &mut Parser, terminator_ch: Option<u8>) -> Option<Command> {

crates/ghostty-vt/src/osc/parsers/semantic_prompt.rs

@@ -3,8 +3,10 @@
 //!
 //! <https://gitlab.freedesktop.org/Per_Bothner/specifications/blob/master/proposals/semantic-prompts.md>
 
-use crate::osc::{Command as OscCommand, Parser, State};
-use crate::string_encoding::{printf_q_decode, url_percent_decode};
+use crate::{
+    osc::{Command as OscCommand, Parser, State},
+    string_encoding::{printf_q_decode, url_percent_decode},
+};
 
 /// Error returned when decoding a command line fails (Zig
 /// `error.DecodeError`).