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/scripts/rendering/entity_renderer.gd

@@ -101,18 +101,9 @@ func _remove_entity_node(entity_id: int) -> void:
 	entity_node.queue_free()
 	entity_nodes.erase(entity_id)
 
-# D-033 color by entity kind (Phase 1: defaults by kind, not relationship)
+# D-033 color by entity kind — delegates to Constants.color_for_entity_kind
 static func _color_for_kind(entity_data: Dictionary) -> Color:
-	var kind_variant: String = entity_data.get("kind", {}).get("variant", "")
-	match kind_variant:
-		"Player":
-			return Constants.ENTITY_COLOR_PLAYER
-		"Npc":
-			return Constants.ENTITY_COLOR_UNKNOWN
-		"Object", "Terrain":
-			return Constants.ENTITY_COLOR_OBJECT
-		_:
-			return Constants.ENTITY_COLOR_OBJECT
+	return Constants.color_for_entity_kind(entity_data)
 
 # Add a facing direction indicator triangle to the player entity
 func _add_facing_indicator(parent_node: Control) -> void: