Add core simulation modules for owniverse mechanics

- Introduced `life_evolution.gd` to manage life evolution processes.
- Implemented `manual_production.gd` for handling production mechanics, including resource management and production steps.
- Created `object_batches.gd` to manage batches of objects, including scaling and appending batches.
- Developed `object_ledger.gd` for tracking physical amounts, available resources, and binding ownerships.
- Added `simulation_module.gd` as a base class for simulation modules, providing a weak reference to the world.
- Established `stellar_rules.gd` for managing stellar evolution and destruction mechanics.
- Introduced `universe_environment.gd` to calculate environmental parameters based on the current state of the universe.

tests/fixtures/legacy_stellar_events.gd

@@ -1,5 +1,5 @@
 extends "res://world/owniverse/owniverse.gd"
 
-# Keep the old materialized-batch path as an independent comparison mode.
-func _uses_short_lived_fast_path(_id: String) -> bool:
-    return false
+# Compare with the materialized-batch path, without overriding the coordinator.
+func _init() -> void:
+    stellar.direct_completions = false