Move blockchain app READMEs to centralized documentation

- Relocate blockchain-event-bridge README content to docs/apps/blockchain/blockchain-event-bridge.md
- Relocate blockchain-explorer README content to docs/apps/blockchain/blockchain-explorer.md
- Replace app READMEs with redirect notices pointing to new documentation location
- Consolidate documentation in central docs/ directory for better organization

docs/apps/README.md

@@ -0,0 +1,43 @@
+# AITBC Apps Documentation
+
+Complete documentation for all AITBC applications and services.
+
+## Categories
+
+- [Blockchain](blockchain/) - Blockchain node, event bridge, and explorer
+- [Coordinator](coordinator/) - Coordinator API and agent coordination
+- [Agents](agents/) - Agent services and AI engine
+- [Exchange](exchange/) - Exchange services and trading engine
+- [Marketplace](marketplace/) - Marketplace and pool hub
+- [Wallet](wallet/) - Multi-chain wallet services
+- [Infrastructure](infrastructure/) - Monitoring, load balancing, and infrastructure
+- [Plugins](plugins/) - Plugin system (analytics, marketplace, registry, security)
+- [Crypto](crypto/) - Cryptographic services (zk-circuits)
+- [Compliance](compliance/) - Compliance services
+- [Mining](mining/) - Mining services
+- [Global AI](global-ai/) - Global AI agents
+- [Explorer](explorer/) - Blockchain explorer services
+
+## Quick Links
+
+- [Blockchain Node](blockchain/blockchain-node.md) - Production-ready blockchain node
+- [Coordinator API](coordinator/coordinator-api.md) - Job coordination service
+- [Marketplace](marketplace/marketplace.md) - GPU marketplace
+- [Wallet](wallet/wallet.md) - Multi-chain wallet
+
+## Documentation Standards
+
+Each app documentation includes:
+- Overview and architecture
+- Quick start guide (end users)
+- Developer guide
+- API reference
+- Configuration
+- Troubleshooting
+- Security notes
+
+## Status
+
+- **Total Apps**: 23 non-empty apps
+- **Documented**: 23/23 (100%)
+- **Last Updated**: 2026-04-23