docs: add # Errors section to Coordinator::set_paused

hive-c0re/src/coordinator.rs

@@ -1471,6 +1471,13 @@ impl Coordinator {
     /// directions: pausing an already-paused agent (or resuming a
     /// running one) is a no-op rather than an error, so the dashboard
     /// toggle and `hivectl pause|resume` don't have to read-then-write.
+    ///
+    /// # Errors
+    ///
+    /// Returns the underlying `io::Error` when the marker can't be
+    /// created (agent dir missing and un-creatable, permissions, disk
+    /// full) or can't be removed. A `NotFound` on removal is *not* an
+    /// error — that's the idempotent resume case.
     pub fn set_paused(name: &hive_types::Ident, paused: bool) -> std::io::Result<()> {
         let marker = Self::agent_paused_marker(name);
         if paused {