feat: SEO and AI discoverability improvements

[eranchetz]

Summary

• Path-based routing: Switch from hash (`/#cloudsql`) to real paths (`/cloudsql/`) so each product tab is indexed as a separate page by search engines — potentially 4-5x more indexed pages
• Build-time page generation: Post-build script generates per-route `index.html` files with unique title, description, canonical, and OG tags — works with S3 static hosting, zero infra changes
• Dynamic head management: `document.title`, meta description, canonical, OG, and Twitter tags update per active tab at runtime
• AI discoverability: New `llms.txt` describing the site, all 5 data endpoints, and their schemas
• Rich structured data: Expanded JSON-LD from 1 schema to 6 — `WebApplication`, `WebSite` with `SearchAction`, and `Dataset` schemas for each pricing dataset (eligible for Google Dataset Search)
• `` fallback: Keyword-rich HTML content for non-JS crawlers (Bing, social link previews, AI crawlers)
• Fix broken assets: Created missing `og-image.png` (1200×630 branded card) and `sitemap.xml` — both were referenced in meta tags / robots.txt but didn't exist
• AlloyDB in meta: Updated title, description, keywords, and OG tags to include AlloyDB
• Backward compatible: Legacy hash URLs (`/#cloudsql?region=...`) auto-redirect to new path format

Files changed

Area	Files
Routing	`src/lib/useUrlState.ts`, `src/App.tsx`, `src/components/McpCliPage.tsx`
Build	`scripts/generate-pages.ts`, `package.json`
SEO assets	`index.html`, `public/og-image.png`, `public/sitemap.xml`, `public/llms.txt`
Tests	`tests/unit/useUrlState.test.ts`

Test plan

• `npm test` — 124 tests pass (including new path-routing tests)
• `npm run build` — generates `dist/{cloudsql,memorystore,alloydb,mcp-cli}/index.html` with unique metadata
• Direct navigation to `/cloudsql/`, `/memorystore/`, `/alloydb/`, `/mcp-cli/` — each serves correct title and canonical URL
• `/sitemap.xml`, `/llms.txt`, `/og-image.png`, `/robots.txt` all return 200
• JSON-LD is valid JSON with all 6 schemas (`WebApplication`, `WebSite`, 4× `Dataset`)
• OG tags patched correctly per route (title, description, url)
• `` fallback content present on all pages
• Legacy hash redirect script covers all non-home pages (`cloudsql`, `memorystore`, `alloydb`, `mcp-cli`)
• `pushState` (SPA tab navigation) and `popstate` (back/forward) present in compiled bundle

🤖 Generated with Claude Code

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