[Phase 1] Write core documentation pages

[afucher]

Write the essential documentation pages for installation, quick start, and basic guides. This enables the site to be deployed and reviewed by users.

Deliverable

A complete set of Markdown documentation files covering installation, quick start, and three core guides (radix, transit, animation). All pages render correctly in Starlight theme.

Acceptance Criteria

• src/content/docs/index.mdx — Introduction page

  • Explains what AstroChart is and is NOT (no ephemeris)
  • Feature table
  • Inline <ChartDemo> showing a basic chart
  • Links to GitHub and npm

• src/content/docs/installation.md — Installation

  • npm/yarn/pnpm install command
  • CDN unpkg link
  • ESM import example
  • UMD global example
  • Note about bundled TypeScript types

• src/content/docs/quickstart.md — Quick Start

  • Step 1: HTML setup
  • Step 2: Data format
  • Step 3: Chart initialization
  • Full copy-pasteable code
  • <ChartDemo> showing output

• src/content/docs/guides/radix-chart.md — Radix Chart

  • Full example with planets, cusps, axis, aspects
  • Explanation of method chain
  • <ChartDemo> live demo

• src/content/docs/guides/transit-chart.md — Transit Chart

  • How to layer transit over radix
  • Transit-to-radix aspects
  • <ChartDemo> showing both rings

• src/content/docs/guides/animation.md — Animation

  • transit.animate() signature
  • Duration, reverse, callback explained
  • <ChartDemo mode="animate"> with interactive button

• All pages have frontmatter with title field

• All pages render without broken links or console errors

• Sidebar updates in astro.config.mjs reflect new pages

• Search index (Pagefind) includes all new pages

• No spelling or grammar errors (run a linter if available)

Related Plan Section

docs-plan.md §4.3 (Page-by-Page Content Spec)