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/mod.rs

@@ -13,7 +13,6 @@ pub struct AgentConfig {
     pub collectors: CollectorConfig,
     pub cache: CacheConfig,
     pub notifications: NotificationConfig,
-    pub collection_interval_seconds: u64,
 }
 
 /// ZMQ communication configuration