Graph SVG has no viewBox, breaks on resize

[CalebisGross]

Problem

`internal/web/static/index.html`: The graph SVG element has no `viewBox` attribute, no `preserveAspectRatio`. The `resizeGraph()` function does a full re-render with 50ms debounce instead of responsive rescaling.

Impact

Graph stretches/squishes on window resize. Switching tabs and returning causes layout issues.

Fix

Add proper SVG viewBox, implement responsive resizing without full re-render.

[CalebisGross]

Fixed in #42 — added viewBox and responsive resize without full re-render.