Heartbeat every 30s while waiting on the approval workflow

The approval handler blocks on handle.result for as long as the
operator takes to decide. AgenticSession only heartbeats between LLM
turns, so a multi-hour wait inside this handler would trigger
heartbeat timeout (default 120s) and kill the activity.

Spawn a Thread that calls Temporalio::Activity::Context.current.heartbeat
every 30s, joined in ensure when handle.result returns. Survives
realistic operator delays.

Existing tests still pass.

Author: lex00

tool_registry_incident_triage/triage_activity.rb

@@ -285,6 +285,24 @@ def self.real_request_human_approval(alert, req)
       # operator should not get a second prompt for the same incident.
       id_conflict_policy: Temporalio::WorkflowIDConflictPolicy::USE_EXISTING
     )
-    handle.result
+
+    # Heartbeat every 30 seconds while waiting on the approval workflow.
+    # AgenticSession only heartbeats between LLM turns, so a multi-hour
+    # operator wait inside this handler would otherwise trigger heartbeat
+    # timeout in 120s and kill the activity.
+    stop = false
+    ticker = Thread.new do
+      until stop
+        sleep 30
+        Temporalio::Activity::Context.current.heartbeat unless stop
+      end
+    end
+
+    begin
+      handle.result
+    ensure
+      stop = true
+      ticker.join
+    end
   end
 end