Implement Phase 10a - Prop Scaling

- Added specifications for Phase 10a, introducing permanent size changes to `.prop` documents and reversible uniform instance scaling in Sandbox EDIT mode.
- Updated `PropCanvas`, `PropAnchorData`, `PropEditor`, `StageGizmos`, `SandboxStage`, and `StageSelection` classes to support new scaling features.
- Implemented document transactions for scaling, including normalization to a 96 px maximum dimension.
- Introduced a new **Transform Whole Prop** tool in the Prop Editor for moving, rotating, and resizing props.
- Created unit tests for the new scaling functionality, validating shape scaling, anchor transformations, and whole-prop interactions.
- Ensured compatibility with existing prop formats and maintained the integrity of the document structure during scaling operations.

scripts/prop_anchor_data.gd

@@ -71,6 +71,48 @@ static func translated_non_origin(anchors: Dictionary, delta: Vector2) -> Dictio
 	normalized[ORIGIN_ID] = _origin()
 	return normalized
 
+static func try_translate_non_origin(anchors: Dictionary, delta: Vector2) -> Dictionary:
+	if not is_finite(delta.x) or not is_finite(delta.y):
+		return {"ok": false, "anchors": {}}
+	var result: Dictionary = normalize_anchors(anchors, false)
+	for id: String in editable_ids(result):
+		var anchor: Dictionary = result[id].duplicate(true)
+		var pos: Vector2 = anchor.get("position", Vector2.ZERO) + delta
+		if not is_finite(pos.x) or not is_finite(pos.y): return {"ok": false, "anchors": {}}
+		anchor["position"] = pos; result[id] = anchor
+	result[ORIGIN_ID] = _origin()
+	return {"ok": true, "anchors": result}
+
+static func try_rotate_non_origin(anchors: Dictionary, angle_rad: float) -> Dictionary:
+	if not is_finite(angle_rad): return {"ok": false, "anchors": {}}
+	var result: Dictionary = normalize_anchors(anchors, false)
+	for id: String in editable_ids(result):
+		var anchor: Dictionary = result[id].duplicate(true)
+		var pos: Vector2 = (anchor.get("position", Vector2.ZERO) as Vector2).rotated(angle_rad)
+		if not is_finite(pos.x) or not is_finite(pos.y): return {"ok": false, "anchors": {}}
+		anchor["position"] = pos
+		anchor["rotation_deg"] = _wrap_deg(float(anchor.get("rotation_deg", 0.0)) + rad_to_deg(angle_rad))
+		result[id] = anchor
+	result[ORIGIN_ID] = _origin()
+	return {"ok": true, "anchors": result}
+
+
+## Returns a fully normalized scaled copy, or {"ok": false} without changing
+## the caller's data when the operation cannot be represented safely.
+static func try_scale_non_origin(anchors: Dictionary, factor: float) -> Dictionary:
+	if not is_finite(factor) or factor <= 0.0:
+		return {"ok": false, "anchors": {}}
+	var normalized: Dictionary = normalize_anchors(anchors, false)
+	for id: String in editable_ids(normalized):
+		var anchor: Dictionary = normalized[id].duplicate(true)
+		var position: Vector2 = anchor.get("position", Vector2.ZERO) * factor
+		if not is_finite(position.x) or not is_finite(position.y):
+			return {"ok": false, "anchors": {}}
+		anchor["position"] = position
+		normalized[id] = anchor
+	normalized[ORIGIN_ID] = _origin()
+	return {"ok": true, "anchors": normalized}
+
 static func normalize_id(candidate: String, anchors: Dictionary) -> String:
 	var id: String = candidate.strip_edges().to_lower()
 	var regex := RegEx.new(); regex.compile("[^a-z0-9]+")