feat: add health module with ECG and EEG visualization components

[crypto-a]

Implement comprehensive medical telemetry visualization module with tree-shakeable subpath exports.

New Components

ECGChart

• Real-time electrocardiogram visualization with Canvas rendering
• Medical-standard ECG grid (1mm/5mm squares)
• Configurable sweep speed (25/50 mm/s) and gain (5/10/20 mm/mV)
• Automatic heart rate calculation using Pan-Tompkins algorithm
• 1mV calibration pulse display
• Full color customization (waveform, grid, background)
• Support for realtime and historical modes
• 60 FPS rendering at 250-1000 Hz sampling rates

EEGChart

• Multi-channel electroencephalogram visualization
• Stacked and overlay layout modes
• Configurable sensitivity (5-100 µV/mm)
• Optional spectral analysis (delta, theta, alpha, beta, gamma bands)
• Support for 4-16+ channels with per-channel colors
• Real-time FFT-based frequency analysis
• Channel labels with 10-20 system naming
• Full color customization

Infrastructure

Build Configuration

• Updated vite.config.ts for multi-entry build (index + health)
• Added package.json subpath export: scadable/health
• Tree-shakeable: zero bundle impact for non-health users
• Generates separate health.{mjs,js,d.ts} files

Utilities

• medicalConstants.ts: ECG/EEG medical standards and defaults
• ecgRenderer.ts: Canvas-based ECG rendering engine
• eegRenderer.ts: Canvas-based multi-channel EEG renderer
• signalProcessing.ts: Filters, peak detection, FFT analysis

Hooks

• useECGAnalysis: R-peak detection and heart rate calculation
• useEEGSpectralAnalysis: Per-channel frequency band analysis

Documentation

• docs/ECGChart.md: Comprehensive ECG component guide
• docs/EEGChart.md: Comprehensive EEG component guide
• Medical disclaimers, best practices, troubleshooting

Storybook

• ECGChart.stories.tsx: 6 stories with realistic ECG waveforms
• EEGChart.stories.tsx: 7 stories with multi-channel brain waves
• Mock devices generating P-QRS-T patterns and frequency bands
• Stories organized under "Health" category
• Existing stories moved to "Basic" category

Technical Details

• Canvas rendering for high-performance (60 FPS)
• Circular buffers for efficient memory usage
• TypedArrays (Float32Array) for data storage
• Medical-grade precision and standards compliance
• Dark mode and custom theme support
• Mobile-responsive with performance optimization

Bundle Size

• Health module: ~28KB (ES), ~19KB (CJS)
• Zero impact on main bundle when not imported