WIP: Output tool via Arc<Mutex<Subconscious>>, ToolHandler to Arc<dyn Fn>

- ToolHandler changed to Arc<dyn Fn(...)> (supports closures)
- Subconscious wrapped in Arc<Mutex<>> on Mind
- init_output_tool() pushes output tool closure capturing the Arc
- Output removed from static memory_tools()
- Most tool handlers wrapped in Arc::new() but some have paren issues

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/agent/tools/read.rs

@@ -8,7 +8,7 @@ pub fn tool() -> super::Tool {
         name: "read_file",
         description: "Read the contents of a file. Returns the file contents with line numbers.",
         parameters_json: r#"{"type":"object","properties":{"file_path":{"type":"string","description":"Absolute path to the file to read"},"offset":{"type":"integer","description":"Line number to start reading from (1-based)"},"limit":{"type":"integer","description":"Maximum number of lines to read"}},"required":["file_path"]}"#,
-        handler: |_a, v| Box::pin(async move { read_file(&v) }),
+        handler: Arc::new(|_a, v| Box::pin(async move { read_file(&v)) }),
     }
 }