fix(client): address PR #22 review — 3 critical bugs, 2 warnings, 8 suggestions

Critical fixes:
- fog_state: guard _compute_bounds() against all-invalid tiles (negative Rect2i crash)
- fog_shader: read Camera2D zoom dynamically instead of hardcoded Vector2(2,2)
- world_radial: set custom_minimum_size in _ready() from spoke geometry

Warnings:
- fog.gdshader: tighten PERIPHERAL_LOW 0.15→0.55 to match D-059 peripheral band
- Extract color_for_entity_kind() to Constants.gd, decouple CursorRenderer from EntityRenderer

Documentation: shallow copy assumption, gradual decay TODO, tween guard rationale,
fade timing rationale, ToggleInsert TODO, monologue consume-once, hover offset safety,
v6 fixture gap TODO.

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

client/ui/interaction_list.gd

@@ -11,6 +11,7 @@ extends Control
 signal verb_selected(kind: String, entity_id: int)
 
 const MAX_VERBS := 4
+# Intentionally faster than cursor 150ms — text must be readable quickly
 const FADE_IN := 0.12
 const FADE_OUT := 0.10
 const LABEL_HEIGHT := 22
@@ -74,7 +75,7 @@ func update_from_state() -> void:
 
 
 func _rebuild_labels() -> void:
-	# Clear existing labels
+	# Guard: tween callback from previous _hide() may fire after labels already freed
 	for lbl in _verb_labels:
 		if is_instance_valid(lbl):
 			lbl.queue_free()
@@ -113,6 +114,7 @@ func _hide() -> void:
 		_active_tween.kill()
 	_active_tween = create_tween()
 	_active_tween.tween_property(self, "modulate:a", 0.0, FADE_OUT)
+	# Guard: tween callback from previous _hide() may fire after labels already freed
 	_active_tween.tween_callback(func():
 		visible = false
 		for lbl in _verb_labels:

client/ui/world_radial.gd

@@ -38,6 +38,9 @@ var _insert_active: bool = false
 
 
 func _ready() -> void:
+	var menu_extent := SPOKE_RADIUS + ICON_SIZE + 20.0  # spoke + icon + label margin
+	custom_minimum_size = Vector2(menu_extent * 2.0, menu_extent * 2.0)
+	size = custom_minimum_size
 	visible = false
 	mouse_filter = Control.MOUSE_FILTER_STOP
 
@@ -117,7 +120,7 @@ func _confirm_selection() -> void:
 
 
 func _activate_insert() -> void:
-	# Send Pause to freeze game while viewing insert data
+	# TODO(v7): replace PAUSE toggle with dedicated ToggleInsert action in protocol
 	if not _insert_active:
 		_insert_active = true
 		_send_pause()