Refactor subagent and workflow domain models; migrate access tiers and events to domain module

- Moved `AccessTier` and `SubagentEvent` enums to `zesdex_domain::subagent`.
- Consolidated workflow-related types into `zesdex_domain::workflow`.
- Updated references across the codebase to use the new domain models.
- Refactored tool execution logic to utilize a new `ToolExecutor` trait.
- Enhanced `AgentTurnService` to handle tool calls and events more effectively.
- Adjusted API handlers and state management to align with new domain structure.

apps/infrastructure/src/subagent/engine.rs

@@ -67,13 +67,13 @@ pub async fn run_agent(
 
     // Limited iteration loop so we don't run forever
     for iteration in 0..MAX_ITERATIONS {
-        let (response_msg, _usage) = client.chat_with_tools_non_streaming(
+        use zesdex_application::ports::ProviderService;
+        let (response_msg, _usage) = client.chat(
             &messages,
             Some(defs.clone()),
             Some(4096),
             None,
-            None,
-        )?;
+        ).await?;
 
         let content = response_msg.content.clone().unwrap_or_default();
         let tool_calls = response_msg.tool_calls.unwrap_or_default();