Refactor agent function names and streamline imports

Unified the naming convention for agent functions across modules to `agent` for consistency. Adjusted relevant imports and cleaned up unused imports in `webhooks.rs` to improve readability and maintainability.

src/agents/mod.rs

@@ -1,4 +1,4 @@
-pub mod news;
-pub mod scrape;
-pub mod search;
-pub mod image_generator;
+pub(crate) mod news;
+pub(crate) mod scrape;
+pub(crate) mod search;
+pub(crate) mod image_generator;