12-Lead ECG View

Extend the ECG display to support a 12-lead view alongside the existing single-lead waveform. Rather than a generic 12-lead generator, ship a curated library of clinically meaningful presentations: Anterior STEMI, Inferior STEMI, Lateral STEMI, Posterior STEMI, LBBB, RBBB, Hyperkalemia (peaked T waves), Pericarditis (diffuse ST elevation with PR depression), Wellens syndrome, AFib in 12-lead view, and VTach in 12-lead view. Controllers select the 12-lead presentation from a dropdown analogous to the existing rhythm dropdown. The monitor renders all 12 leads in the standard 3x4 grid layout with a rhythm strip at the bottom. Single-lead view remains the default; controllers toggle into 12-lead mode when the scenario calls for it. Pairs with the cardiac scenario library - STEMI scenarios should auto-suggest the appropriate 12-lead presentation when loaded.