[Phase 2] Gallery page and advanced demo features

[afucher]

Create a gallery page showcasing all rendering modes and optional advanced demo features.

Deliverable

An optional but useful Gallery page showing all chart rendering modes side-by-side, plus enhanced demo interactivity.

Acceptance Criteria

• src/pages/gallery.astro created with:

  • Basic radix chart demo
  • Radix with aspects
  • Transit over radix
  • Animated transit (with Play button)
  • Stroke-only mode demo
  • Custom colors demo (sign colors overridden)
  • Each demo is a <ChartDemo> component
  • Gallery is linked from navbar or sidebar

• Optional: Settings playground (deferred if time-constrained):

  • Interactive color picker or text inputs for key settings
  • Chart re-renders as settings change
  • Shows how to customize settings in real time

• Optional: Zero-result search tracking scaffolding:

  • Placeholder script in website/public/track-search.js
  • Documented but not active (will be enabled when analytics are added)

• Gallery page is mobile-responsive

• All demos load and run without errors

Related Plan Section

docs-plan.md §6 (Visual & Interactive Examples) — Gallery Page subsection