Doors run on the mission clock instead of being replicated

A door's position was an integrated countdown owned by whichever machine
the map-entity round-robin happened to deal it to. That left doors one
one-way-latency behind on every other machine, re-acquired at each state
change; drifting permanently on any frame hitch over a second, which the
old code dropped outright rather than clamping; and frozen mid-cycle,
collision volumes included, when their owning peer left, since ownership
transfer is not implemented.

Doors are clockwork with no inputs, and door/VTV physics is already local
pointer access - VTV::ProcessCollision reads door->currentVelocity off
the local object and the crush test is local VTV state - so a door does
not need an owner at all. Door::SlideDoor is now a phase function of
Application::GetMissionElapsed(), anchored so phase zero reproduces the
original DefaultState entry: fully open, starting to close. Every host
builds its own doorframe out of the map stream as a HermitInstance, the
instance kind DynamicEntityCreation does not broadcast, so nothing is
sent, nothing is received, and a peer leaving takes no doors with it.

Verified against a copy of the old integrator at 25fps with the real 10s
travel / 3s dead timings: identical 26s cycle, a constant one-frame
offset, and no drift across a 3s stall that leaves the old code
permanently 3 seconds out of phase.

Also fixes a latent bug found on the way: UpdateManager iterates the
dynamic master socket, which holds Independant and Hermit instances as
well as masters, and handed all of them to EntityUpdateReplicants, which
asserts MasterInstance.

Doorframes no longer consume a slot in the map-entity ownership cursor,
which shifts who owns every map entity dealt after them, so this cannot
share a session with an older build. The lobby publishes a simulation
revision and refuses to launch a mixed room.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

MUNGA/APP.cpp

@@ -273,6 +273,35 @@ Scalar
 	return mgr->GetFrameRate();
 }
 
+//
+//#############################################################################
+// GetMissionElapsed
+//#############################################################################
+//
+Scalar
+	Application::GetMissionElapsed()
+{
+	Check(this);
+
+	//
+	//--------------------------------------------------------------------------
+	// gameStarted is only ever stamped by RunMissionMessageHandler, so before
+	// the race it is uninitialized - and entities that are pre-runnable do get
+	// performed before then.  Answer zero until the clock actually exists.
+	//--------------------------------------------------------------------------
+	//
+	if (
+		GetApplicationState() != RunningMission
+		 && GetApplicationState() != EndingMission
+	)
+	{
+		return 0.0f;
+	}
+
+	Scalar elapsed = Now() - gameStarted;
+	return (elapsed > 0.0f) ? elapsed : 0.0f;
+}
+
 //
 //#############################################################################
 // Initialize