Every node records DMARC and TLS results for the aggregate reports

The report scheduler dropped DMARC and TLS events on a node whose role
lacks outboundMta (upstream never started it there, so they sat in a
channel nobody read). Mail received on a front node therefore never
reached an aggregate report, which is meant to cover all of a domain's
inbound mail, whichever node received it. In rehearsal, five messages
received on port 25 on a front node were missing from every report.

- The report scheduler records on every node. Recording is a store write
  the nodes already share, so it needs nothing from the outbound MTA.
  Building and sending a report (the DmarcReport and TlsReport tasks) stay
  with outboundMta nodes, as the task manager already enforces.
- More nodes now append to one report at once. Appends already guard the
  report's versioned primary key; a write that loses now retries up to ten
  times after a short random pause, not three times at once.
- The node sending a report deletes it only if it is unchanged since it
  was read, and reads it again otherwise, so a record another node appends
  meanwhile goes out with the report instead of being deleted unsent.

Test: cluster::front_reports (PostgreSQL and MySQL). A front node's
results appear in the report the MTA node sends, alongside eight appended
at once from both nodes, and the front node never runs the report task.
It fails on main: the front node's results are never recorded.

crates/smtp/src/lib.rs

@@ -47,8 +47,10 @@ impl SpawnQueueManager for IpcReceivers {
         // inbuxa: upstream started these only when the node's role included
         // outboundMta at boot, so turning the role on later did nothing and
         // turning it off left them delivering until a restart. They now run
-        // on every node and follow the role live (see Queue::start and the
-        // report scheduler). This also drains the queue channel on nodes
+        // on every node: the queue follows the role live (see Queue::start),
+        // and the report scheduler records DMARC and TLS results on every
+        // node, whatever its role (see reporting/scheduler.rs). This also
+        // drains the queue channel on nodes
         // without the role, where every queued message's refresh used to sit
         // in a channel nobody read until it filled and queueing blocked.
         if !core.storage.registry.is_recovery_mode() {