Fix Online Softmax: move subplot titles inside chart area (y=0.95)

Fix Online Softmax charts: increase height (350px), margins, and y-axis range for labels

Fix Memory Hierarchy: move labels further right (x=0.65), shorten arrow

Fix Memory Hierarchy diagram: move transfer labels to right of arrow

Fix Visualizer tab bugs: softmax data, reset button, causal toggle

Phase 2: Add Visualizer tab with tiling animation, online softmax, and memory hierarchy