feat: match fire demon to supplied references

[ytvee]

Role and design intent

Implemented as a senior creative technologist / real-time graphics engineer, using the supplied references as the structural source of truth for silhouette, face, node hierarchy, fire palette and detached ember behaviour.

Summary

• adds a compact 72 × 72 density field derived from the warm reference and samples it at runtime to reproduce the broad body, crown tongues, raised side shapes and lower contour;
• rebuilds the graph as layered body, rim, arm, eye, pupil, mouth, starburst and ember systems;
• makes the eyes substantially larger and denser, preserves compact black pupils and builds a wider open smile;
• increases graph density and mixes micro-nodes with large Obsidian-style hubs;
• expands the colour gradient from yellow/amber through orange/red to magenta/violet and occasional blue tips;
• adds stronger idle convection, thermal waves, particle flicker, size breathing and edge pulses so the demon visibly burns while idle;
• deepens drag propagation to seven graph steps so nodes can stretch the demon across the complete hero section;
• keeps the visual field borderless and the initial desktop composition offset to the right;
• replaces the background with twelve much smaller, denser code columns covering the full section;
• keeps code behind the canvas and reveals it only through a speed-sensitive torch mask and warm haze while dragging;
• preserves Astro static HTML, adaptive density, lazy Three.js loading, reduced-motion support and deterministic SVG fallback.

Verification

GitHub Actions completed successfully:

• dependency installation — passed;
• graph and physics tests — passed;
• Astro strict type checking — passed;
• production build — passed.

Closes #4