Fix OOM crashes during screenshot comparison

[djette-st]

Summary

• Recycle captured bitmap in createBitmapFromActivity() after saving to disk, eliminating ~9.6 MB leaked per test invocation
• Switch buffer allocation to native memory using ByteBuffer.allocateDirect() instead of IntBuffer.allocate(), moving ~19.2 MB of buffer allocation off the JVM heap entirely
• Add try/finally guards in ParallelPixelProcessor.analyze() and transform() to guarantee buffer cleanup on exceptions
• Recycle diff bitmap in HighContrastDiff.generate() after saving to disk
• Add overflow guard in allocateSafely() for large capacity * INTEGER_BYTES computations, widening LowMemoryException.requestedAllocation to Long

Context

The library intermittently crashes with LowMemoryException / OutOfMemoryError when the instrumentation process receives a small JVM heap (as low as 16 MB) despite the emulator having 2 GB of RAM. The root cause is a combination of bitmap leaks and heap-based buffer allocation that exhausts the constrained JVM heap.

Peak JVM heap during comparison was ~48 MB (captured bitmap leak + reloaded bitmap + baseline bitmap + two IntBuffers). With these fixes, IntBuffers move to native memory and the leaked bitmap is recycled, reducing peak heap to ~19.2 MB (just the two bitmaps, whose pixel storage is native on API 26+).

Test plan

• All Library unit tests pass
• All Library androidTests pass (56 tests)
• LegacySample screenshot tests pass (88 tests)
• FlixSample screenshot tests pass (20 tests)
• FlixLibrary screenshot tests pass (3 tests)
• Plugin unit tests pass
• KtLint checks pass for all modules
• Build validation passes for Accessibility, ComposeExtensions, FullscreenCaptureMethod, Plugin
• Verify on emulator with constrained heap (16 MB) that OOM no longer occurs