devrel: SDKs, examples, docs site, and training materials

[TheNewAutonomy]

Goal

Provide a developer-friendly onboarding path: docs, SDKs, sample code, and training material.

Scope

• SDKs (at least JS/TS; optionally Python) for:
  • signing + submitting txs
  • querying balances/receipts
  • subscribing to events (service bus)
• Sample apps:
  • simple wallet interaction
  • indexer/subgraph example
  • webhooks example
• Publish documentation structure (can start in-repo, later move to a site)

Acceptance criteria

• A developer can build and deploy a simple dapp/backend against Catalyst in <1 day using provided materials
• Examples are versioned and tested against testnet

Refs: docs/ directory, #187 (RPC epic), #238 (web2 APIs).