feat(runtime): first-entry conductor sequences local-player world entry

Cutover slice C3a: the resumable transaction that dissolves the C3
flip's circularity finding. RuntimeLocalPlayerFirstEntryState drives the
local player's complete entry in retail's own order — authored-mover
preparation (the makeObject/set_description shape analog, via a pure
no-submit extraction TryPrepareAuthoredMover), the publication chain's
off-canonical Prepare + atomic body Commit against the residence's exact
placement token, the Evaluate/CommitActivation enter-world analog, the
Place-receipt acknowledgement as that act's virtualized completion, and
only then the executor's FIFO drain (retail: enter_world at 93824
strictly precedes ProcessObjectNetBlobs at 93831). Five stages, eight
typed statuses, exactly-once per stage under retry, no second token
copies, and an acknowledge-stage discriminator that separates
not-yet-FIFO-head (retryable) from authority-moved (typed abandonment) —
a mid-flight delete can no longer strand a retry-forever entry.

The residence retirement notification becomes an ordered multicast
(snapshot-iterated per the event-stream precedent), the lifetime
constructs the conductor with a late-bind Publication seam (transactional
unbound failure — no mutation before the throw), deletion/reset converge
the conductor automatically through the same choke points as the
executor, and its active count is in the ownership snapshot and
IsConverged. Dormant: no production Advance caller; GameRuntime binding
is C3c's first act.

Reviewed: retail-conformance PASS (the stage order verified
step-for-step against retail's entry sequence; the live-controller-on-
abandonment invariant proven structurally enforced and retail-correct —
retail has no entry-flow rollback) + architecture/adversarial PASS after
one fix round (acknowledge-stage authority discrimination; the wiring
fold; two prescribed pre-C3c hardenings). Runtime 948/948; complete
Release solution green across all nine projects.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AcDream.Runtime/Physics/RuntimeSetPositionState.cs

@@ -1576,11 +1576,69 @@ internal sealed class RuntimeSetPositionState : IDisposable
         uint scatterAttempts = 0u,
         float shadowWorldOffsetX = 0f,
         float shadowWorldOffsetY = 0f)
+    {
+        outcome = default;
+
+        RuntimeSetPositionMoverPreparationStatus status =
+            TryPrepareAuthoredMover(
+                record,
+                token,
+                operationKind,
+                flags,
+                collisionSource,
+                gameTime,
+                out RuntimeSetPositionCommand command,
+                placementClass,
+                portal,
+                line,
+                scatterRadiusX,
+                scatterRadiusY,
+                scatterAttempts,
+                shadowWorldOffsetX,
+                shadowWorldOffsetY);
+        if (status != RuntimeSetPositionMoverPreparationStatus.Prepared)
+            return status;
+
+        outcome = SubmitPreparedPlacement(token, command);
+        return RuntimeSetPositionMoverPreparationStatus.Prepared;
+    }
+
+    /// <summary>
+    /// C3a: the exact-Setup-read + <see cref="PrepareMover"/> half of
+    /// <see cref="TryPrepareAndSubmitAuthoredPlacement"/>, extracted (pure
+    /// refactor, byte-identical behavior for the existing caller above) so
+    /// the dormant local-player first-entry conductor
+    /// (<c>AcDream.Runtime.Gameplay.RuntimeLocalPlayerFirstEntryState</c>)
+    /// can obtain a prepared <see cref="RuntimeSetPositionCommand"/> WITHOUT
+    /// the trailing <see cref="SubmitPreparedPlacement"/> call. Submission
+    /// through the ordinary tail is exactly what an operation with
+    /// <c>DormantLocalActivation</c> set must never receive — see
+    /// <see cref="RetryDeferred"/>'s "must never bypass that path through the
+    /// ordinary remote CommitCanonical tail" comment; the dormant chain's own
+    /// Evaluate/Commit/FinalizeActivation methods are the sole substitute for
+    /// submission on that path.
+    /// </summary>
+    internal RuntimeSetPositionMoverPreparationStatus TryPrepareAuthoredMover(
+        RuntimeEntityRecord record,
+        in RuntimeEntityPlacementToken token,
+        RuntimeSetPositionOperationKind operationKind,
+        PhysicsSetPositionFlags flags,
+        IPreparedCollisionSource collisionSource,
+        double gameTime,
+        out RuntimeSetPositionCommand command,
+        PhysicsPlacementClass placementClass = PhysicsPlacementClass.Ordinary,
+        RuntimePortalPlacementAuthority portal = default,
+        Vector3 line = default,
+        float scatterRadiusX = 0f,
+        float scatterRadiusY = 0f,
+        uint scatterAttempts = 0u,
+        float shadowWorldOffsetX = 0f,
+        float shadowWorldOffsetY = 0f)
     {
         EnsureNotDisposed();
         ArgumentNullException.ThrowIfNull(record);
         ArgumentNullException.ThrowIfNull(collisionSource);
-        outcome = default;
+        command = default;
 
         uint setupTableId = CanonicalSetupTableId(record);
         RuntimeSetPositionMoverSetup setup;
@@ -1615,13 +1673,7 @@ internal sealed class RuntimeSetPositionState : IDisposable
             shadowWorldOffsetX,
             shadowWorldOffsetY,
             portal);
-        RuntimeSetPositionMoverPreparationStatus status = PrepareMover(
-            token, preparation, out RuntimeSetPositionCommand command);
-        if (status != RuntimeSetPositionMoverPreparationStatus.Prepared)
-            return status;
-
-        outcome = SubmitPreparedPlacement(token, command);
-        return RuntimeSetPositionMoverPreparationStatus.Prepared;
+        return PrepareMover(token, preparation, out command);
     }
 
     internal bool IsExactPreparedPlacementCurrent(