feat: add zCode Swarm — multi-agent orchestration system

- 6 agent skills: code-review, performance, security, architecture, test, git
- 4 coordinator modes: hierarchical, mesh, gossip, consensus
- Federated memory system (6 namespaces)
- Neural network agent recommendation
- Agent marketplace (plugin discovery/install)
- Real-time dashboard + performance metrics
- CRDT-based sync for decentralized modes
- 22 files, ~1400 lines total

Inspired by ruflo distributed multi-agent patterns.

.zcode/marketplace/architecture-analyzer.json

@@ -0,0 +1,9 @@
+{
+  "name": "architecture-analyzer",
+  "id": "architecture-analyzer",
+  "version": "1.0.0",
+  "description": "Analyze codebase architecture for design patterns, coupling, cohesion, and SOLID principles.",
+  "author": "zCode Swarm",
+  "capabilities": ["pattern_validation", "coupling_analysis", "cohesion_check", "solid_principles"],
+  "icon": "🏗️"
+}