Refactor item grabbing logic and remove TileGrabber

Moved item grabbing and auto-arrange logic from the separate TileGrabber node into the player.gd script, consolidating server/client authority checks and RPC handling for multiplayer. Removed obsolete tile_grabber.gd and its UID file. Updated main.tscn to clean up unused UI nodes and adjust visibility settings for player boards.

scenes/main.tscn

@@ -74,6 +74,7 @@ grow_vertical = 2
 theme_override_styles/panel = ExtResource("5_dvx6y")
 
 [node name="NetworkInfo" type="VBoxContainer" parent="NetworkPanel"]
+layout_mode = 0
 offset_left = 8.0
 offset_right = 124.0
 offset_bottom = 50.0
@@ -90,7 +91,6 @@ horizontal_alignment = 1
 vertical_alignment = 1
 
 [node name="PlayerboardUI" type="GridContainer" parent="."]
-visible = false
 clip_contents = true
 anchors_preset = 2
 anchor_top = 1.0
@@ -1056,44 +1056,6 @@ environment = ExtResource("4_ky38j")
 
 [node name="CanvasLayer" type="CanvasLayer" parent="."]
 
-[node name="MarginContainer" type="Control" parent="."]
-visible = false
-clip_contents = true
-layout_direction = 2
-layout_mode = 3
-anchors_preset = 5
-anchor_left = 0.5
-anchor_right = 0.5
-offset_left = -248.0
-offset_top = 24.0
-offset_right = 275.0
-offset_bottom = 129.0
-grow_horizontal = 2
-
-[node name="Panel4" type="Panel" parent="MarginContainer"]
-custom_minimum_size = Vector2(105, 105)
-layout_mode = 2
-offset_left = 137.0
-offset_right = 242.0
-offset_bottom = 105.0
-theme_override_styles/panel = SubResource("StyleBoxTexture_5oeq4")
-
-[node name="Panel5" type="Panel" parent="MarginContainer"]
-custom_minimum_size = Vector2(105, 105)
-layout_mode = 2
-offset_left = 275.0
-offset_right = 380.0
-offset_bottom = 105.0
-theme_override_styles/panel = SubResource("StyleBoxTexture_5oeq4")
-
-[node name="Panel6" type="Panel" parent="MarginContainer"]
-custom_minimum_size = Vector2(105, 105)
-layout_mode = 2
-offset_left = 413.0
-offset_right = 518.0
-offset_bottom = 105.0
-theme_override_styles/panel = SubResource("StyleBoxTexture_5oeq4")
-
 [node name="AllPlayerGoals" type="HBoxContainer" parent="."]
 y_sort_enabled = true
 clip_contents = true
@@ -6052,6 +6014,7 @@ grow_vertical = 2
 texture = ExtResource("10_my1qp")
 
 [node name="AllPlayerBoards" type="TabContainer" parent="."]
+visible = false
 clip_contents = true
 anchors_preset = 4
 anchor_top = 0.5