broker: sqlite-backed (survives hive-c0re restart)

hive-c0re/src/coordinator.rs

@@ -2,7 +2,7 @@
 //! sockets: the broker plus a map of `name -> AgentSocket`.
 
 use std::collections::HashMap;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::sync::{Arc, Mutex};
 
 use anyhow::{Context, Result};
@@ -18,11 +18,12 @@ pub struct Coordinator {
 }
 
 impl Coordinator {
-    pub fn new() -> Self {
-        Self {
-            broker: Arc::new(Broker::new()),
+    pub fn open(db_path: &Path) -> Result<Self> {
+        let broker = Broker::open(db_path).context("open broker")?;
+        Ok(Self {
+            broker: Arc::new(broker),
             agents: Mutex::new(HashMap::new()),
-        }
+        })
     }
 
     pub async fn register_agent(&self, name: &str) -> Result<PathBuf> {