systems rework: buffs, prestige graph, research, modular architecture

Decouples core systems from centralized globals in favor of catalogue-based architecture and data-driven content.

   Key changes:
   - Prestige: node-based buff tech tree, graph panel, progress bar
   - Research: multi-worker system, per-generator research, xp generation
   - Ascension: meta-currency layer via multi-currency prestige resets
   - Buffs: refactored as generator-independent via catalogues
   - UI: currency panel, edge-scrolling camera + zoom, current-goal panel
   - Alchemy Tower: crafting building with recipe/cost system
   - Testing: 7 test suites (ascension, prestige, research, goals)
   - Content: migrated from hardcoded idles/ to gym format (tiny_sword)

docs/gyms/tiny_sword/buildings/castle/castle.gd

@@ -0,0 +1,20 @@
+extends Node2D
+
+@onready var _prestige_panel: PrestigePanel = $PrestigePanel
+
+# Called when the node enters the scene tree for the first time.
+func _ready() -> void:
+	pass # Replace with function body.
+
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(delta: float) -> void:
+	pass
+
+func _on_area_2d_mouse_entered() -> void:
+	## TODO: remove this comment to enable prestige panel
+	#_prestige_panel.visible = true
+	pass
+
+func _on_area_2d_mouse_exited() -> void:
+	_prestige_panel.visible = false