feat: deep SEO optimization — metadata, OG tags, sitemap, structured data, GA4

- Add metadataBase and localized generateMetadata to all pages (EN/FR)
- Add Open Graph and Twitter card defaults with branded OG image
- Add canonical URLs and hreflang alternates on every page
- Create robots.ts (allow all, block /admin/ and /api/)
- Create sitemap.ts with all routes x 2 locales and hreflang
- Add Organization, WebSite, and CreativeWork JSON-LD structured data
- Add GA4 (G-LD348WF8EM) with Consent Mode v2 (default denied for EEA)
- Add llms.txt for AI discoverability
- Add production nginx config for letsbe.biz

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/llms.txt

@@ -0,0 +1,31 @@
+# LetsBe.
+
+> Bespoke digital studio — custom web design, software, AI integration, and private infrastructure.
+
+LetsBe. is a digital studio founded by Matt Ciaccio, serving clients worldwide from the Côte d'Azur, France. We design and build custom websites, purpose-built software, and manage private digital infrastructure — all under one roof.
+
+## Services
+
+- **Web Design & Development**: Custom websites and web applications designed from scratch, built for performance and SEO.
+- **Software & Platforms**: CRMs, management tools, dashboards, booking systems, and API integrations built around your workflow.
+- **Hosting & Infrastructure**: Dedicated servers, email, cloud storage, security, and monitoring — fully owned by the client.
+- **AI Integration**: Intelligent features, automation, and data intelligence woven into websites and software.
+
+## Selected Work
+
+- [Monaco Ocean Protection Challenge](/work/monaco-ocean): AI-powered judging and analytics platform for a Mediterranean conservation event.
+- [Port Nimara](/work/port-nimara): Custom website and CRM for marina lead management and operations.
+- [Port Amador](/work/port-amador): Website and private digital infrastructure for a premium marina.
+
+## Key Pages
+
+- [Home](https://letsbe.biz)
+- [Services](https://letsbe.biz/services)
+- [About](https://letsbe.biz/about)
+- [Start a Project](https://letsbe.biz/#configure)
+
+## Contact
+
+- Email: hello@letsbe.biz
+- LinkedIn: https://www.linkedin.com/company/letsbe-digital
+- X: https://x.com/letsbe_digital