docs: event sourcing positioning, npm keywords, and ecosystem links - #54

Improves discoverability of the TypeScript client and keeps its public description accurate to the breadth of the Chronicle ecosystem.

• README leads with "Event sourcing for TypeScript and Node.js" and adds npm, build, MIT, and Discord badges.
• Adds an accurate breadth paragraph: Chronicle's .NET SDK plus TypeScript, Kotlin/Java (JVM), and Elixir clients (Python coming soon), and pluggable storage providers (MongoDB default; PostgreSQL, SQL Server, SQLite).
• Lists client capabilities readers search for: transactions, jobs, webhooks, compliance/PII, and OpenTelemetry.
• Adds a "The Cratis ecosystem" section cross-linking Chronicle, the other clients, Arc, Components, CLI + Workbench, the experimental model-first layer, supporting projects, and Samples.
• Source/README.md (rendered on npm) gets the same positioning with absolute links plus an install snippet.
• Source/package.json gains search keywords (event-sourcing, event-store, cqrs, ddd, projections, grpc, ...), an event-sourcing description, and a homepage link to the docs site.

No code changes; documentation and package metadata only.