agent: switch from tokio::sync::Mutex to std::sync::Mutex

The agent lock is never held across await points — turns lock briefly,
do work, drop, then do async API calls. std::sync::Mutex works and
can be locked from sync contexts (screen tick inside terminal.draw).

Fixes: blocking_lock() panic when called inside tokio runtime.

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

src/agent/tools/mod.rs

@@ -29,7 +29,7 @@ fn default_timeout() -> u64 { 120 }
 /// Async tool handler function.
 /// Agent is None when called from contexts without an agent (MCP server, subconscious).
 pub type ToolHandler = fn(
-    Option<std::sync::Arc<tokio::sync::Mutex<super::Agent>>>,
+    Option<std::sync::Arc<std::sync::Mutex<super::Agent>>>,
     serde_json::Value,
 ) -> Pin<Box<dyn Future<Output = anyhow::Result<String>> + Send>>;
 
@@ -94,11 +94,11 @@ pub async fn dispatch(
 pub async fn dispatch_with_agent(
     name: &str,
     args: &serde_json::Value,
-    agent: Option<std::sync::Arc<tokio::sync::Mutex<super::Agent>>>,
+    agent: Option<std::sync::Arc<std::sync::Mutex<super::Agent>>>,
 ) -> String {
     // Look up in agent's tools if available, otherwise global
     let tool = if let Some(ref a) = agent {
-        let guard = a.lock().await;
+        let guard = a.lock().unwrap();
         guard.tools.iter().find(|t| t.name == name).copied()
     } else {
         None