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/currencies/gold.tres

@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="Currency" format=3 uid="uid://w4u1hddplb4e"]
+
+[ext_resource type="Texture2D" uid="uid://d3nymghus6x3" path="res://sandbox/tiny_swords/UI Elements/UI Elements/Icons/Icon_03.png" id="1_n656e"]
+[ext_resource type="Script" uid="uid://dtgqjf3bl7pm8" path="res://core/currency/currency.gd" id="2_vohw6"]
+
+[resource]
+script = ExtResource("2_vohw6")
+id = &"gold"
+display_name = "Gold"
+icon = ExtResource("1_n656e")
+always_visible = true