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/tests/sandbox/integration/mod.rs

@@ -4,8 +4,8 @@ mod file_operations;
 #[cfg(test)]
 mod network_operations;
 #[cfg(test)]
-mod system_info;
-#[cfg(test)]
 mod process_isolation;
 #[cfg(test)]
-mod violations; 
+mod system_info;
+#[cfg(test)]
+mod violations;