## Why

Step 001 established brand tokens and fonts — we now have a working Astro project but every page must manually construct its own `<html>` document with head meta tags. Step 002 creates the shared `BaseLayout.astro` shell so all subsequent pages start from a consistent, SEO-complete foundation without repetition.

## What Changes

- **New**: `src/layouts/BaseLayout.astro` — HTML document shell accepting props for title, description, locale, canonical URL, alternate URL, OG image, and JSON-LD structured data
- **New**: `src/components/Nav.astro` — empty stub (filled in step 003)
- **New**: `src/components/Footer.astro` — empty stub (filled in a later step)
- **New**: `src/content/en.json` — initial structure with global meta fields (site name, default title, default description, default OG image path)
- **New**: `src/content/nl.json` — Dutch translations of the same global meta fields
- **New**: `src/content/i18n.ts` — helper that loads and returns the correct JSON content object based on locale string
- **Update**: `src/pages/index.astro` — replace manual `<html>` shell with `<BaseLayout>`, passing appropriate props

## Capabilities

### New Capabilities

- `base-layout`: HTML document shell providing consistent `<head>` (charset, viewport, favicon, Archia font preloads, canonical link, hreflang alternates, OG tags, Twitter card tags) and `<body>` defaults (Midnight background, Snow text, Archia font), with stub nav/footer and content/JSON-LD slots
- `content-i18n`: File-based content loading system — JSON files per locale (`en.json`, `nl.json`) plus an `i18n.ts` helper function that returns the correct content object given a locale string

### Modified Capabilities

- `brand-tokens`: No requirement changes — the existing spec covers colors, fonts, and gradient; BaseLayout consumes these tokens but does not change them

## Impact

- All future pages (`/`, `/about`, `/ai-launchpad`, `/contact`, `/privacy`, plus `/nl/*` variants) will import and use `BaseLayout`
- SEO: adds canonical URL, hreflang (`en` ↔ `nl`), OG tags, and Twitter card tags to every page
- Affects `en.json` / `nl.json` content structure (introduces the `meta` key)
- No new npm dependencies — uses only Astro built-ins and TypeScript
