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/tools/mod.rs

@@ -30,6 +30,7 @@ pub mod spawn;
 pub mod utility;
 pub mod web_search;
 pub mod workflow;
+pub mod executor;
 
 pub use git::git_cred;
 pub use git::git_operator;