docs: update documentation links and expand Q2-Q3 2026 milestone plan

- Fix broken documentation links in intro.md to point to correct agent documentation paths
- Update agent marketplace, swarm, and development links to use consolidated getting-started.md
- Expand Q2-Q3 2026 milestone plan from "OpenClaw Agent Economic Model & Scalability" to "Global Marketplace Expansion"
- Add comprehensive global infrastructure scaling strategy with multi-region deployment
- Include cross-chain agent economics

docs/8_development/2_setup.md

@@ -71,6 +71,6 @@ AITBC_NETWORK=testnet
 
 ## Next Steps
 
-- [API Authentication](api-authentication.md)
-- [Python SDK](sdks/python.md)
-- [Examples](examples.md)
+- [API Authentication](../6_architecture/3_coordinator-api.md#authentication)
+- [Python SDK](../2_clients/1_quick-start.md)
+- [Examples](../2_clients/2_job-submission.md)