Fix autograding test failures: Add JUnit Platform launcher for Gradle 9.2.1 and correct mask values

[Copilot]

CI autograding tests failed with Gradle 9.2.1 while passing locally with Gradle 8.10 due to missing JUnit Platform launcher dependency and incorrect mask values in button click logic.

Changes

build.gradle

• Added junit-platform-launcher:1.8.1 as testRuntimeOnly dependency
• Required by Gradle 9.2.1; implicitly provided in 8.10

ToggleGameEngine.java

• Fixed mask values missing leading zeros in setMask()
• Buttons 2, 4, 5, 6, 7, 8 now correctly padded to 9 characters

// Before
mask.put(2, "11001000");   // Wrong: 8 chars
mask.put(8, "1011");       // Wrong: 4 chars

// After  
mask.put(2, "011001000");  // Correct: 9 chars
mask.put(8, "000001011");  // Correct: 9 chars

The mask values are XOR'd with the 9-character board state, so length mismatch caused incorrect toggle behavior.

Original prompt

I don't know why the Autograding Tests are failing, when they did pass when I ran them locally

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