fix(replica): send each object's real age as time_since_created_on_server

Live sent the milliseconds since the object was created on the server in
every construction header (nonzero in 142,258 of 145,677 captured
constructions; the same object constructed again later carries a larger
value by the time elapsed; the local player's own construction on load is
0). DLU always wrote 0. The client stores it in the object's config
(LWOGameObject::time_since_created_on_server).

Entities now remember when they were created (steady clock) and write
their age.

Test: ReplicaConstructionTest.TimeSinceCreatedOnServerIsTheObjectsAge.

Check in game: zone in and walk around several worlds; objects, NPCs,
enemies and other players appear and animate as before (no objects
popping, stuck or misplaced animations on platforms/spinners).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/dGameTests/dComponentsTests/CMakeLists.txt

@@ -15,6 +15,7 @@ set(DCOMPONENTS_TESTS
 	"ReplicaComponentOrderTests.cpp"
 	"QuickBuildCompleteTests.cpp"
 	"RocketLaunchTests.cpp"
+	"ReplicaConstructionTests.cpp"
 )
 
 # Get the folder name and prepend it to the files above