Move transmission interval to ZMQ config section

- Changed code to use zmq.transmission_interval_seconds instead of top-level collection_interval_seconds
- Removed collection_interval_seconds from AgentConfig
- Updated validation to check zmq.transmission_interval_seconds
- Improves config organization by grouping all ZMQ settings together

Bump version to v0.1.210

Co-Authored-By: Claude <noreply@anthropic.com>

agent/src/config/validation.rs

@@ -11,9 +11,9 @@ pub fn validate_config(config: &AgentConfig) -> Result<()> {
         bail!("ZMQ bind address cannot be empty");
     }
 
-    // Validate collection interval
-    if config.collection_interval_seconds == 0 {
-        bail!("Collection interval cannot be 0");
+    // Validate ZMQ transmission interval
+    if config.zmq.transmission_interval_seconds == 0 {
+        bail!("ZMQ transmission interval cannot be 0");
     }
 
     // Validate CPU thresholds