feat: SEO schema improvements, title optimization, and GitHub profile README (#90)

## Summary

Technical SEO and schema improvements per the trust/positioning audit (marcus/market#4, marcus/content#11).

## Changes

### Event Schema + SpeakableSpecification (`src/components/SEO.astro`)
- Added JSON-LD `Event` schemas for all 3 signature talks (50 First Dates with AI, From Strip-Mining to Cultivation, The Soil Under Your Team)
- `performer: Scott Scoble`, `offers`, and `description` on each
- Added `SpeakableSpecification` schema for voice search / Google Assistant / AI Overviews compatibility

### Book Schema Enhancements (`src/components/SEO.astro`)
- Updated book author fields to `Person` objects with URL
- Added book descriptions
- Added `sameAs` Amazon canonical links for "The Soil Beneath the Code" and "A Walk in Mentoring"

### Homepage Title Tag (`src/pages/index.astro`)
- Changed from "Scott Scoble — Human Cultivation Expert for the AI Age" to "Scott Scoble — Keynote Speaker | Human Cultivation Expert for the AI Age"
- Adds the high-value "Keynote Speaker" keyword for speaker bureau search

### Homepage h1 Accessibility (`src/pages/index.astro`)
- Added `aria-label="The human cultivation expert for the AI age."` to the decorative span-based h1
- Preserves visual design; improves semantic structure for search engines

### GitHub Profile README (`github-profile-README.md`)
- Professional bio with links to scott.scoble.me, books, speaker profile
- Ready to deploy to `sscoble/sscoble` GitHub profile repo

## Verification

- Build passes: 25 pages generated
- All JSON-LD schemas confirmed in output
- No visual regressions

## Related

- marcus/market#4: SEO name disambiguation strategy
- marcus/content#11: Content distribution strategy

Co-authored-by: Scott Scoble <scott@scoble.me>
Co-authored-by: agent-content <agent-content@scoble.me>
Reviewed-on: https://os.scoble.me/forgejo/forgejo/sscoble/brand-site/pulls/90
Co-authored-by: engineering Agent <engineering@marcus.local>
Co-committed-by: engineering Agent <engineering@marcus.local>

github-profile-README.md

@@ -0,0 +1,37 @@
+# Scott Scoble
+
+**Keynote Speaker · Consultant · Author**  
+Human Cultivation Expert for the AI Age
+
+---
+
+I help leaders and teams build AI systems that cultivate humans instead of strip-mining them.
+
+## What I Do
+
+- **Keynotes & workshops** on AI, leadership, and team cultivation — [speaking page](https://scott.scoble.me/speaking)
+- **Consulting** for engineering orgs adopting AI without burning out their people — [consulting page](https://scott.scoble.me/consulting)
+- **Writing** books and articles on the human side of technology — [blog](https://scott.scoble.me/blog)
+
+## Books
+
+- **[The Soil Beneath the Code](https://a.co/d/0226o4Hg)** (2023) — What engineering teams can learn from farmers about sustainable systems
+- **[A Walk in Mentoring](https://a.co/d/0bRKZeUV)** (2024) — Three questions that change how people learn
+- **Dark Provenance** (2026) — Formal verification for the AI age
+
+## Projects
+
+- **[OpenClaw](https://github.com/sscoble)** — Multi-agent orchestration system
+- **[Speckl](https://github.com/sscoble/speckl)** — Formal verification for distributed systems
+- **[MeOS](https://github.com/sscoble)** — Personal operating system for the agentic era
+
+## Find Me
+
+- 🌐 [scott.scoble.me](https://scott.scoble.me)
+- 💼 [linkedin.com/in/scottscoble](https://linkedin.com/in/scottscoble)
+- 🐦 [x.com/scottscoble](https://x.com/scottscoble)
+- 📧 scott@scoble.me
+
+---
+
+> *"The most successful AI teams aren't the ones with the best models. They're the ones who stopped strip-mining their humans and started cultivating them."*