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/workflow/hive_mind/synthesis.rs

@@ -4,7 +4,7 @@ use anyhow::Result;
 use tracing::info;
 
 use crate::tools::ToolCtx;
-use crate::workflow::hive_mind::types::NodeOutput;
+use zesdex_domain::workflow::NodeOutput;
 
 /// Synthesize a consensus from all node outputs.
 ///