HostHandler: senders for the AA tranche messages

A host couldn't drive the new messages through the HostHandler class —
only the server side knew how to dispatch them.  Adds six new senders
plus a unit test that walks each through a real loopback connection:

  * send_legacy_remote_command  -> S2F21
  * send_event_report_request   -> S6F15
  * send_individual_report_request -> S6F19
  * send_annotated_report_request  -> S6F21
  * send_pp_load_inquire        -> S7F1
  * send_delete_pp              -> S7F17

Suite: 296 cases / 1571 assertions.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_host_handler.cpp

@@ -100,6 +100,20 @@ struct Recorder {
         return gem::s16f6_pr_job_command_ack(gem::HostCmdAck::Accept);
       if (msg.stream == 14 && msg.function == 9)
         return gem::s14f10_create_control_job_ack("CJ-1", gem::ObjectAck::Success);
+      // New senders (Task 18): provide canned replies so the host's
+      // send_*_request transactions complete instead of timing out.
+      if (msg.stream == 2 && msg.function == 21)
+        return gem::s2f22_remote_command_ack(gem::HostCmdAck::Accept);
+      if (msg.stream == 6 && msg.function == 15)
+        return gem::s6f16_event_report_data({0, 300, {}});
+      if (msg.stream == 6 && msg.function == 19)
+        return gem::s6f20_individual_report_data({});
+      if (msg.stream == 6 && msg.function == 21)
+        return gem::s6f22_annotated_report_data({});
+      if (msg.stream == 7 && msg.function == 1)
+        return gem::s7f2_pp_load_grant(gem::ProcessProgramAck::Accept);
+      if (msg.stream == 7 && msg.function == 17)
+        return gem::s7f18_delete_pp_ack(gem::ProcessProgramAck::Accept);
       // Unhandled — leave the host to time out on T3.
       return std::nullopt;
     };
@@ -254,6 +268,47 @@ TEST_CASE("HostHandler: E40/E94 job creation senders produce correct wire") {
   pump_until(w.io, [&] { return cmd_ack; });
 }
 
+TEST_CASE("HostHandler: new senders produce correct wire shapes") {
+  // Wires up the host + equipment, installs the handler, fires each
+  // new sender, and verifies the (stream, function) of the request
+  // the equipment received.  The equipment auto-acks each via Recorder.
+  Wired w;
+  Recorder rec;
+  w.equipment->set_message_handler(rec.handler());
+  w.handler->install();
+  w.host->start();
+  w.equipment->start();
+  bool selected = false;
+  w.host->set_selected_handler([&] { selected = true; });
+  pump_until(w.io, [&] { return selected; });
+
+  auto run_one = [&](auto fire, uint8_t want_stream, uint8_t want_fn) {
+    bool done = false;
+    fire([&](std::error_code ec, const s2::Message&) {
+      REQUIRE_FALSE(ec);
+      done = true;
+    });
+    pump_until(w.io, [&] { return done; });
+    REQUIRE_FALSE(rec.last.empty());
+    CHECK(rec.last.back().stream == want_stream);
+    CHECK(rec.last.back().function == want_fn);
+  };
+
+  run_one([&](auto cb) { w.handler->send_legacy_remote_command("PAUSE", cb); },
+          2, 21);
+  run_one([&](auto cb) { w.handler->send_event_report_request(300, cb); }, 6, 15);
+  run_one([&](auto cb) { w.handler->send_individual_report_request(1, cb); },
+          6, 19);
+  run_one([&](auto cb) { w.handler->send_annotated_report_request(1, cb); },
+          6, 21);
+  run_one([&](auto cb) {
+    w.handler->send_pp_load_inquire("RECIPE-X", 4096, cb);
+  }, 7, 1);
+  run_one([&](auto cb) {
+    w.handler->send_delete_pp({"RECIPE-X", "RECIPE-Y"}, cb);
+  }, 7, 17);
+}
+
 TEST_CASE("HostHandler: inbound S5F1 alarm auto-acks with S5F2") {
   Wired w;
   // Equipment side stays silent on inbound; we only need the host to