Initial import of the CBDDC codebase with docs and tests. Add a .NET-focused gitignore to keep generated artifacts out of source control.

docs/deployment-modes.md

@@ -0,0 +1,82 @@
+# CBDDC Deployment Mode
+
+ZB.MOM.WW.CBDDC.Hosting supports a single deployment mode.
+
+## Single-Cluster Mode
+
+**Best for:**
+- Dedicated database servers
+- Simple deployments
+- Development/testing environments
+- Small-to-medium applications
+
+### Architecture
+
+```
+┌─────────────────────┐
+│   ASP.NET Server    │
+│                     │
+│  ┌───────────────┐  │
+│  │    CBDDC      │  │
+│  │  (1 cluster)  │  │
+│  └───────────────┘  │
+│         │           │
+│    [TCP:5001]       │
+└─────────────────────┘
+```
+
+### Configuration
+
+```csharp
+builder.Services.AddCBDDCHostingSingleCluster(options =>
+{
+    options.NodeId = "server-01";
+    options.TcpPort = 5001;
+});
+```
+
+### Characteristics
+
+- One database per server instance
+- Simple configuration
+- Easy to scale horizontally (multiple servers = multiple databases)
+- No port collision issues
+- Recommended for most use cases
+
+## Server Behavior
+
+Servers use respond-only operation:
+
+- Accept incoming TCP sync connections
+- Respond to sync requests
+- Serve data to clients
+- Maintain persistence
+- Do not initiate outbound sync
+- Do not perform UDP discovery
+- Do not connect to other servers automatically
+
+## Persistence Layer Compatibility
+
+Single-cluster mode works with all persistence providers:
+
+| Provider | Support | Notes |
+|----------|---------|-------|
+| SQLite (Direct) | Yes | One DB file per cluster |
+| EF Core | Yes | Flexible DB options |
+| PostgreSQL | Yes | Best for production |
+
+## Scaling Strategy
+
+### Horizontal Scaling
+
+```
+Load Balancer
+     │
+     ├─> Server 1 (Cluster A) [PostgreSQL A]
+     ├─> Server 2 (Cluster B) [PostgreSQL B]
+     └─> Server 3 (Cluster C) [PostgreSQL C]
+```
+
+## Recommendation
+
+Use single-cluster mode for ASP.NET hosting. It is simpler, robust, and straightforward to scale.