Add world indicators and parameters to enhance universe simulation

- new universe creation function.

autoload/save_manager.gd

@@ -7,6 +7,7 @@ const SAVE_PATH = "user://settings.cfg"
 
 const FORMAT_VERSION: int = 2
 const SimulationTime = preload("res://world/owniverse/simulation_time.gd")
+const WorldParameters = preload("res://world/owniverse/world_parameters.gd")
 const STATE_VERSION: String = SimulationTime.STATE_VERSION
 var last_error: String = ""
 var blocked_saves: Dictionary = {}
@@ -229,8 +230,25 @@ static func _validate_payload(data: Variant, speed_limit: int, stages: Array) ->
         "planet_remainders", "blast_remainders", "destruction_remainders", "civilization_remainders",
         "civilization_stats", "civilization_homes", "ethics", "stats",
     ]
-    if saved.size() != required.size():
-        return "unsupported state structure"
+    # Optional additions to the current format. Saves predating indicators keep
+    # their quantities and receive neutral defaults from Owniverse on load.
+    for field in saved:
+        if field not in required and field not in ["world_parameters", "trends"]:
+            return "unsupported state structure"
+    if saved.has("world_parameters"):
+        if not _number_map(saved.world_parameters) or saved.world_parameters.size() != WorldParameters.defaults().size():
+            return "invalid state.world_parameters"
+        for key in WorldParameters.defaults():
+            if not saved.world_parameters.has(key) or saved.world_parameters[key] < 1.0:
+                return "invalid world parameter " + key
+            if key in ["Bur", "Exp", "Agg"] and saved.world_parameters[key] > 19.0:
+                return "invalid world scale " + key
+    if saved.has("trends"):
+        if not _number_map(saved.trends) or saved.trends.size() != WorldParameters.TRENDS.size():
+            return "invalid state.trends"
+        for key in WorldParameters.TRENDS:
+            if not saved.trends.has(key) or saved.trends[key] >= 1.0:
+                return "invalid trend " + key
     for field in required:
         if not saved.has(field):
             return "missing state." + field