feat(#2569): DB-backed per-agent todo store + mcp.sock upsert/clear/list/mark-done ops

hive-c0re/src/loose_ends.rs

@@ -97,9 +97,36 @@ pub fn for_agent(coord: &Coordinator, agent: &str) -> Result<Vec<LooseEnd>> {
             age_seconds: saturating_age(now, r.created_at.timestamp()),
         });
     }
+    // Dynamic, subsystem-pushed todos (loose-ends v2, #2569). Scoped to
+    // this agent; the producing subsystem or the agent itself clears them.
+    out.extend(todos_for(coord, agent, None)?);
     Ok(out)
 }
 
+/// This agent's dynamic todos as `LooseEnd::Todo` rows, optionally
+/// filtered to one `subsystem`. Shared by [`for_agent`] and the
+/// `ListTodos` handler so the row-mapping lives in one place.
+pub fn todos_for(
+    coord: &Coordinator,
+    agent: &str,
+    subsystem: Option<&str>,
+) -> Result<Vec<LooseEnd>> {
+    let now = now_unix();
+    Ok(coord
+        .todos
+        .list(agent, subsystem)?
+        .into_iter()
+        .map(|t| LooseEnd::Todo {
+            id: t.id,
+            subsystem: t.subsystem,
+            subsystem_key: t.subsystem_key,
+            summary: t.summary,
+            source: t.source,
+            age_seconds: saturating_age(now, t.updated_at.timestamp()),
+        })
+        .collect())
+}
+
 /// Hive-wide loose-ends view: EVERY pending approval + EVERY
 /// unanswered question + EVERY pending reminder. Manager surface
 /// only; sub-agents can't see each other's threads via the agent