README.md: project landing page and chapter index

[yagop]

Write the repository README.md - the landing page for the Build Your Own Coding Agent tutorial. The full source material lives in OUTLINE.md; the README is the reader-facing front door.

Goal: A newcomer can land on the repo, understand what they will build, set up their environment, and navigate to any chapter.

What it should contain

• Title + one-paragraph pitch (build a coding agent with the Anthropic SDK on TypeScript + Bun; ends as a streaming, tool-using Telegram + REPL agent).
• Who it is for / prerequisites (Bun, Anthropic API key, Telegram bot token from BotFather, basic TypeScript).
• Quick start: bun add @anthropic-ai/sdk, .env setup (ANTHROPIC_API_KEY, TELEGRAM_BOT_TOKEN), and how to run an example (bun run examples/01-sdk-first-request/hello.ts).
• Repository layout (the examples/NN-slug/ convention).
• Table of contents linking to each chapter (10 issues / chapter docs).
• Conventions note (TypeScript + Bun, official @anthropic-ai/sdk, ASCII punctuation).
• Status / contributing note (each chapter is tracked by its own issue: Chapter 1: The Claude SDK and Your First API Request #1-Chapter 10: Real-World Patterns: Research, Automation, and Support #10).
• License.

Chapter index to link

1. #1 The Claude SDK and Your First API Request
2. #2 Streaming Responses and Message Types
3. #3 Handling User Requests: REPL and Telegram Bot
4. #4 Context and Conversation Management
5. #5 Implementing Tools and Function Calling
6. #6 Building Tool Chains and Complex Workflows
7. #7 Advanced Agent Patterns
8. #8 Production and Deployment
9. #9 Advanced Topics: RAG, Prompt Engineering, and Fine-Tuning
10. #10 Real-World Patterns: Research, Automation, and Support

Definition of done

• README.md written and committed to main.
• All chapter links resolve (to chapter docs once written, or to their tracking issues).
• Quick start verified end-to-end on a clean clone.
• ASCII punctuation only.