Implement civilization flow mechanics and profiling for resource allocation

- Added `civilization_flow.gd` to manage continuous expected flows and resource allocation within civilizations.
- Introduced `allocate_profiled` and `whole_quotas` functions in `quantity_math.gd` for precise stock allocation based on float shares.
- Enhanced `credit` logic in `object_ledger.gd` to handle production remainders more effectively.
- Updated `append_batch` in `object_batches.gd` to prevent batch creation for invalid IDs.
- Introduced `ratio_approx` function in `exact.gd` for better handling of float profiles.
- Added a benchmark script `benchmark_civilization_flows.gd` to evaluate the performance of civilization flow mechanics.
- Refactored various functions to improve clarity and efficiency in handling resource flows and allocations.

tests/benchmark_full_ui.gd

@@ -40,7 +40,7 @@ func run():
     for id in stage.owniverse.catalog.entities:
         if E.gt(stage.owniverse.ledger.physical_amount(stage.owniverse.state, id), 0): remaining_objects += 1
     print("Remaining objects: ", remaining_objects)
-    print("Final adaptive step: ", stage.owniverse.frame_step_seconds)
+    print("Simulation step: ", stage.owniverse.frame_step_seconds)
     for entity in stage.owniverse.catalog.entities.values(): entity.free()
     stage.owniverse.free()
     scene.free()