Enhance civilization flow mechanics and adaptive quality control

- Implemented runtime-only adaptive quality controller to optimize simulation performance based on CPU time.
- Added adaptive quality thresholds and recovery cycles to dynamically adjust simulation fidelity.
- Introduced single-step solving method for civilization transitions to improve performance under high loads.
- Updated benchmark scripts to include speed parameter for testing various simulation speeds.
- Added tests for adaptive quality adjustments and their effects on civilization flow calculations.
- Documented results of optimization attempts and their impact on performance metrics.

tests/test_adaptive_quality.gd

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+extends SceneTree
+
+var checks: int = 0
+var failures: int = 0
+
+func _initialize() -> void:
+	call_deferred("run")
+
+func check(condition: bool, message: String) -> void:
+	checks += 1
+	if not condition:
+		failures += 1
+		push_error(message)
+
+func run() -> void:
+	var world = load("res://world/owniverse/owniverse.gd").new()
+	world.update_adaptive_quality(250000)
+	check(world.adaptive_quality == 2, "A slow cycle selects the medium approximation")
+	world.update_adaptive_quality(250000)
+	check(world.adaptive_quality == 3, "A slow medium-approximation cycle selects the coarse mode")
+	check(world.adaptive_generation_phase == 1, "Coarse generation phase alternates")
+	for i in 36: world.update_adaptive_quality(100000)
+	check(world.adaptive_quality == 2, "Thirty consecutive recovery cycles lower quality by one level")
+	for i in 30: world.update_adaptive_quality(100000)
+	check(world.adaptive_quality == 1, "Sustained headroom lowers quality gradually")
+	for i in 30: world.update_adaptive_quality(100000)
+	check(world.adaptive_quality == 0, "The exact mode returns after sustained headroom")
+
+	var rows: Array = []
+	for node in 12:
+		var edges: Dictionary = {}
+		var outgoing: float = 0.0
+		if node < 6:
+			edges[node + 6] = 0.25
+			outgoing = 0.25
+		rows.append({"edges": edges, "outgoing": outgoing})
+	var generator: Dictionary = {"rows": rows, "index": {"source": 0}}
+	var solved: Dictionary = world.civilization_flow._solve_single_step(generator, "source", 2.0)
+	for ethic in 6:
+		var mass: float = 0.0
+		var occupation: float = 0.0
+		for node in range(ethic, 12, 6):
+			mass += solved.mass[node]
+			occupation += solved.occupation[node]
+		check(absf(mass - 1.0) < 1e-12, "Approximate transition conserves ethic mass %d" % ethic)
+		check(absf(occupation - 2.0) < 1e-12, "Approximate transition conserves integrated time %d" % ethic)
+
+	world.free()
+	print("Adaptive quality: %d checks, %d failures" % [checks, failures])
+	quit(1 if failures else 0)