fix: three bug fixes - library XP scaling, prep time floor, dual design slot logic

Fixes #297: Library room XP now uses 25× rate without undocumented floor multiplier
Fixes #305: Prep time mana-per-tick now applies Math.floor(capacity/50) per spec
Fixes #304: Dual design slot correctly returns false when first slot is empty

docs/circular-deps.txt

@@ -1,5 +1,5 @@
 # Circular Dependencies
-Generated: 2026-06-08T12:54:52.991Z
+Generated: 2026-06-08T12:59:39.710Z
 Found: 1 circular chain(s) — these MUST be fixed before modifying involved files.
 
 1. 1) stores/golem-combat-actions.ts > stores/golem-combat-helpers.ts

docs/dependency-graph.json

@@ -1,6 +1,6 @@
 {
   "_meta": {
-    "generated": "2026-06-08T12:54:50.978Z",
+    "generated": "2026-06-08T12:59:37.733Z",
     "description": "Import dependency graph for src/lib/game. Keys are files, values are arrays of files they import.",
     "usage": "To find what a file affects, search for its path in the VALUES. To find what a file depends on, look at its KEY entry."
   },