refactor: clean up test suite and apply code formatting

Remove redundant/obsolete tests from intel_400x_tests.rs, retaining core test coverage for Intel400x common functionality. Apply rustfmt formatting to intel_4002.rs and state machine test files.

Changes:

- Remove ~40 redundant test functions from intel_400x_tests.rs

- Apply rustfmt formatting to intel_4002.rs

- Fix import formatting in state machine tests

- Clean up trailing whitespace

tests/intel_4003_state_machine_test.rs

@@ -131,7 +131,10 @@ fn test_intel_4003_state_machine_progression() {
     // The shift register operation requires proper state machine transitions.
     // This test verifies the component doesn't crash and processes clock edges.
     // Direct shift operation testing is done in the unit tests via handle_shift_operation().
-    println!("Shift register state after clock cycles: 0x{:03X}", shift_reg_value);
+    println!(
+        "Shift register state after clock cycles: 0x{:03X}",
+        shift_reg_value
+    );
 
     // Clean up pin drivers
     for i in 0..4 {