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-renderer/src/opengl/pipeline.rs

@@ -1,6 +1,12 @@
 //! Wrapper for handling render pipelines (`opengl/Pipeline.zig`).
 use super::gl::{
-    self, AttribType, FramebufferTarget, Gl, RawFramebuffer, RawProgram, RawVertexArray,
+    self,
+    AttribType,
+    FramebufferTarget,
+    Gl,
+    RawFramebuffer,
+    RawProgram,
+    RawVertexArray,
 };
 
 /// Vertex step function.