feat: introduce workflow management tools and commands

- Added new workflow commands: `/workflow` to open the workflow panel and `/workflow run <prompt>` to execute workflows.
- Implemented `spawn_agents` and `spawn_pipeline` tools for parallel and sequential task execution, respectively.
- Enhanced workflow engine to handle real-time agent status updates and display in the UI.
- Updated workflow panel to show agent statuses, findings count, and session counters.
- Refactored existing code to integrate new workflow functionalities and improve overall structure.

src/tool/mod.rs

@@ -18,6 +18,7 @@ pub mod seqthink;
 pub mod shell;
 pub mod shell_filter;
 pub mod utility;
+pub mod spawn;
 pub mod workflow;
 
 /// Common interface every agent-invocable tool implements: name, JSON schema, and execution.
@@ -150,6 +151,8 @@ pub fn all_tools() -> Vec<Box<dyn Tool>> {
         Box::new(super::tool::plan::PlanReady),
         Box::new(super::tool::workflow::WorkflowRun),
         Box::new(super::tool::workflow::NoteFinding),
+        Box::new(super::tool::spawn::SpawnAgents),
+        Box::new(super::tool::spawn::SpawnPipeline),
         Box::new(super::tool::memory::remember::Remember),
         Box::new(super::tool::memory::forget::Forget),
         Box::new(super::tool::memory::recall::Recall),