Wire boundary hooks into player movement

Movement now evaluates boundary enter/exit conditions. Exit checks can
block movement based on carrying items (by name or tag). Enter and exit
messages sent when crossing boundary borders. All boundary logic lives
in move_player() before position update.

src/mudlib/commands/movement.py

@@ -74,6 +74,41 @@ async def move_player(player: Player, dx: int, dy: int, direction_name: str) ->
         await player.send("You can't go that way.\r\n")
         return
 
+    # Check boundary exit conditions
+    current_boundary = None
+    target_boundary = None
+
+    for boundary in zone.boundaries:
+        if boundary.contains(player.x, player.y):
+            current_boundary = boundary
+        if boundary.contains(target_x, target_y):
+            target_boundary = boundary
+
+    # If leaving a boundary with an exit check, evaluate it
+    if (
+        current_boundary is not None
+        and current_boundary is not target_boundary
+        and current_boundary.on_exit_check
+        and current_boundary.on_exit_check.startswith("carrying:")
+    ):
+        check_value = current_boundary.on_exit_check[9:]  # strip "carrying:"
+        # Check if player has any item matching name or tag
+        from mudlib.thing import Thing
+
+        has_item = False
+        for obj in player._contents:
+            if isinstance(obj, Thing) and (
+                obj.name == check_value or check_value in obj.tags
+            ):
+                has_item = True
+                break
+
+        if has_item:
+            # Check failed, block movement
+            if current_boundary.on_exit_fail:
+                await player.send(f"{current_boundary.on_exit_fail}\r\n")
+            return
+
     # If painting, place the brush tile at the current position before moving
     if player.paint_mode and player.painting:
         zone.terrain[player.y][player.x] = player.paint_brush
@@ -88,6 +123,23 @@ async def move_player(player: Player, dx: int, dy: int, direction_name: str) ->
     player.x = target_x
     player.y = target_y
 
+    # Send boundary messages
+    # If leaving a boundary (and check passed), send exit message
+    if (
+        current_boundary is not None
+        and current_boundary is not target_boundary
+        and current_boundary.on_exit_message
+    ):
+        await player.send(f"{current_boundary.on_exit_message}\r\n")
+
+    # If entering a boundary, send enter message
+    if (
+        target_boundary is not None
+        and target_boundary is not current_boundary
+        and target_boundary.on_enter_message
+    ):
+        await player.send(f"{target_boundary.on_enter_message}\r\n")
+
     # Check for auto-trigger portals at new position
     portals_here = [
         obj for obj in zone.contents_at(target_x, target_y) if isinstance(obj, Portal)