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>

include/secsgem/gem/data_model.hpp

@@ -3,6 +3,7 @@
 #include "secsgem/gem/store/alarms.hpp"
 #include "secsgem/gem/store/carriers.hpp"
 #include "secsgem/gem/store/clock.hpp"
+#include "secsgem/gem/ept_state.hpp"
 #include "secsgem/gem/store/control_jobs.hpp"
 #include "secsgem/gem/store/equipment_constants.hpp"
 #include "secsgem/gem/store/event_reports.hpp"
@@ -41,6 +42,7 @@ struct EquipmentDataModel {
   CarrierStore              carriers;
   LoadPortStore             load_ports;
   SubstrateStore            substrates;
+  EptStateMachine           ept;
 
   // Convenience: VID -> value lookup spanning SVIDs and DVIDs.
   std::optional<s2::Item> vid_value(uint32_t vid) const {