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/5_reference/5_zk-proofs.md

@@ -154,8 +154,8 @@ bool verified = verifier.verifyAndRecord(
 
 ## Documentation
 
-- [ZK Technology Comparison](zk-technology-comparison.md)
-- [Circuit Design](zk-receipt-attestation.md)
+- [ZK Technology Comparison](#technology-comparison)
+- [Circuit Design](#zk-circuit-design)
 - [Development Guide](./5_zk-proofs.md)
 - [API Documentation](../6_architecture/3_coordinator-api.md)