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/currency_panel.tscn

@@ -0,0 +1,15 @@
+[gd_scene format=3 uid="uid://cur_panel_scene_uid"]
+
+[ext_resource type="Script" uid="uid://9_vbox" path="res://core/currency/currency_panel.gd" id="1_cpnl"]
+
+[node name="CurrencyPanel" type="PanelContainer" unique_id=3000000001]
+custom_minimum_size = Vector2(250, 340)
+offset_left = 5.0
+offset_top = 5.0
+offset_right = 255.0
+offset_bottom = 345.0
+script = ExtResource("1_cpnl")
+
+[node name="CurrencyTiles" type="VBoxContainer" parent="." unique_id=3000000002]
+layout_mode = 2
+theme_override_constants/separation = 4