feat(net+app): Phase B.3 — portal-space state machine for teleports

PlayerTeleport (0xF751) is a standalone GameMessage (u16 sequence,
align-4). When received, WorldSession fires TeleportStarted(uint sequence).

GameWindow subscribes: OnTeleportStarted sets PlayerMovementController.State
= PortalSpace, freezing all WASD/physics input. OnLivePositionUpdated
detects arrival (different landblock or >100 unit jump on our character guid),
recenters the streaming origin, resolves physics for ground Z, snaps the
player entity + controller, returns State to InWorld, and sends
GameActionLoginComplete directly (matching holtburger's PlayerTeleport
handler: send_login_complete on every portal transition).

PlayerMovementController gains PlayerState enum + early-return guard: if
State == PortalSpace, Update() returns a zero-movement result immediately
so no MoveToState / AutonomousPosition messages are emitted during transit.

WorldSession gains ResetLoginComplete() for callers that need to re-arm
the latch (documented; not called by the teleport path since we send
LoginComplete directly rather than through the PlayerCreate latch).

Opcode source: holtburger/crates/holtburger-protocol/src/opcodes.rs:84
Wire layout: holtburger/crates/.../movement/messages/teleport.rs

Build: 0 errors. Tests: 283 passed, 0 failed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/AcDream.App/Input/PlayerMovementController.cs

@@ -33,6 +33,14 @@ public readonly record struct MovementResult(
     float? SidestepSpeed,
     float? TurnSpeed);
 
+/// <summary>
+/// Portal-space state for the player movement controller.
+/// PortalSpace freezes all movement input while the server is moving the
+/// player through a portal — resumed once the destination UpdatePosition
+/// arrives and the player is snapped to the new location.
+/// </summary>
+public enum PlayerState { InWorld, PortalSpace }
+
 /// <summary>
 /// Per-frame player movement controller. Reads input, drives the
 /// physics engine, tracks motion state for animation + server messages.
@@ -60,6 +68,15 @@ public sealed class PlayerMovementController
     public float GravityAccel { get; set; } = 20f;
     public float AirControlFactor { get; set; } = 0.2f;
 
+    /// <summary>
+    /// Current portal-space state. Set to PortalSpace when the server sends
+    /// PlayerTeleport (0xF751); set back to InWorld once the destination
+    /// UpdatePosition arrives and the player is snapped to the new cell.
+    /// While in PortalSpace, Update returns immediately with a zero-movement
+    /// result so no WASD input or physics is processed.
+    /// </summary>
+    public PlayerState State { get; set; } = PlayerState.InWorld;
+
     public float Yaw { get; set; }
     public Vector3 Position { get; private set; }
     public uint CellId { get; private set; }
@@ -87,6 +104,24 @@ public sealed class PlayerMovementController
 
     public MovementResult Update(float dt, MovementInput input)
     {
+        // Portal-space guard: while teleporting, no input is processed and
+        // no physics is resolved. Return a zero-movement result so the caller
+        // can detect the frozen state (MotionStateChanged = false, no commands).
+        if (State == PlayerState.PortalSpace)
+        {
+            return new MovementResult(
+                Position: Position,
+                CellId: CellId,
+                IsOnGround: !IsAirborne,
+                MotionStateChanged: false,
+                ForwardCommand: null,
+                SidestepCommand: null,
+                TurnCommand: null,
+                ForwardSpeed: null,
+                SidestepSpeed: null,
+                TurnSpeed: null);
+        }
+
         // 1. Apply turning from keyboard + mouse.
         if (input.TurnRight)
             Yaw -= TurnSpeed * dt;