docs: v2.0 documentation — guides, reference, and examples

[Siddhant-K-code]

Adds complete documentation for Distill v2.0 features.

What's included

Guides

• Getting started — install, configure, first API call
• Memory — store, recall, expire, supersede, sensitivity, conflicts, decay
• Sessions — create, push context, compression strategies
• MCP — Claude Desktop and Cursor integration
• Deployment — Docker, binary, Fly.io, Render, observability

Reference

• API — all REST endpoints with auth details
• Configuration — config file, env vars, CLI flags

Examples

• LangChain integration with a DistillMemory wrapper
• RAG pipeline with dedup, recall, supersession, and sessions

Closes #8