Register a new task server with the proxy
Unique identifier (alphanumeric and hyphens only)
Human-readable name (optional, defaults to Server ID)
Full base URL including protocol (http:// or https://)
Select at least one task type that this server supports
Load balancing weight (default: 10, higher = more traffic)
Maximum number of concurrent tasks (default: 100)
Optional JSON metadata (must be valid JSON object)