F2: EPT joined to EquipmentDataModel + server-side CEID emission

EquipmentDataModel now carries an EptStateMachine as a value member
alongside the other top-level state machines.  Server installs a
state-change handler that maps every EPT transition to a CEID emission
through the existing emit_event path:

  1100 NonScheduledTime    1103 Engineering
  1101 ScheduledDowntime   1104 Standby
  1102 UnscheduledDowntime 1105 Productive

CEIDs land in the 1100+ block to keep clear of the demo equipment.yaml
(100s/200s/400s) and E90 (900s).  Log lines include the dwell time of
the previous state so trace-level diagnostics show utilization without
extra tooling.

Application code drives transitions by calling model->ept.on_event(...);
the existing event-report machinery (subscription state, S6F11
batching, spool) gates wire emission so EPT events spool on offline
hosts like every other CEID.

Closes Tranche F — E116 Equipment Performance Tracking end-to-end.

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

apps/secs_server.cpp

@@ -16,6 +16,7 @@
 #include "secsgem/endpoint.hpp"
 #include "secsgem/gem/control_state.hpp"
 #include "secsgem/gem/data_model.hpp"
+#include "secsgem/gem/e116_constants.hpp"
 #include "secsgem/gem/e90_constants.hpp"
 #include "secsgem/gem/messages.hpp"
 #include "secsgem/gem/router.hpp"
@@ -340,6 +341,30 @@ int main(int argc, char** argv) {
         }
       });
 
+  // ---- E116 EPT state-change emitter -----------------------------------
+  model->ept.set_state_change_handler(
+      [logfn, emit_event](gem::EptState from, gem::EptState to,
+                          gem::EptEvent ev, std::chrono::milliseconds dwell) {
+        logfn(std::string("EPT: ") + gem::ept_state_name(from) + " -> " +
+              gem::ept_state_name(to) + "  (" + gem::ept_event_name(ev) +
+              ", dwelt " + std::to_string(dwell.count()) + "ms)");
+        switch (to) {
+          case gem::EptState::NonScheduledTime:
+            emit_event(gem::e116::kCeidNonScheduledTime); break;
+          case gem::EptState::ScheduledDowntime:
+            emit_event(gem::e116::kCeidScheduledDowntime); break;
+          case gem::EptState::UnscheduledDowntime:
+            emit_event(gem::e116::kCeidUnscheduledDowntime); break;
+          case gem::EptState::Engineering:
+            emit_event(gem::e116::kCeidEngineering); break;
+          case gem::EptState::Standby:
+            emit_event(gem::e116::kCeidStandby); break;
+          case gem::EptState::Productive:
+            emit_event(gem::e116::kCeidProductive); break;
+          case gem::EptState::NoState: break;
+        }
+      });
+
   // ---- Build the SECS dispatch table once -------------------------------
   gem::Router router;