style: apply cargo fmt across entire Rust codebase

- Remove Rust formatting check from CI workflow since formatting is now applied
- Standardize import ordering and organization throughout codebase
- Fix indentation, spacing, and line breaks for consistency
- Clean up trailing whitespace and formatting inconsistencies
- Apply rustfmt to all Rust source files including checkpoint, sandbox, commands, and test modules

This establishes a consistent code style baseline for the project.

src-tauri/src/lib.rs

@@ -1,11 +1,11 @@
 // Learn more about Tauri commands at https://tauri.app/develop/calling-rust/
 
 // Declare modules
-pub mod commands;
-pub mod sandbox;
 pub mod checkpoint;
-pub mod process;
 pub mod claude_binary;
+pub mod commands;
+pub mod process;
+pub mod sandbox;
 
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {