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/commands/mod.rs

@@ -1,6 +1,6 @@
-pub mod claude;
 pub mod agents;
-pub mod sandbox;
-pub mod usage;
+pub mod claude;
 pub mod mcp;
-pub mod screenshot; 
+pub mod sandbox;
+pub mod screenshot;
+pub mod usage;