Fix animation input highlighting, guard animation start, and robust image-based output colormap

[kowshik24]

Motivation

• Prevent animation errors when the output matrix is absent or invalid and ensure input-region highlighting matches the padded coordinate space used in output calculation.
• Handle invalid output size scenarios gracefully in the UI instead of trying to render empty matrices.
• Improve image-based output visualization to avoid divide-by-zero/NaN colors and provide a consistent blue/red colormap for positive/negative activations.

Description

• Add a guard in startAnimation to return early if outputMatrix is empty or malformed to avoid runtime errors when starting an animation.
• Change the input-region coordinate math in animateStep to use the padded coordinate space (remove - padding offsets), compute paddedHeight/paddedWidth, and check indices against the padded dimensions when highlighting input cells.
• Add an early exit in updateVisualization when outputHeight or outputWidth is <= 0 that stops animation, clears matrices, and displays an error message.
• Replace min/max normalization for image-based output cells with a max-absolute-based intensity normalization to avoid divide-by-zero and produce stable blue-to-red coloring for negative/positive values.

Testing

• No automated tests were run for this change.

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Codex Task