feat: use authored category names for mods

Store categories as authored strings. Trim and deduplicate without changing case, compare without case sensitivity, and keep all observed categories available to filters and editors.

manifest.json

@@ -4,7 +4,7 @@
   "version": "0.1.0",
   "author": "ct",
   "description": "A battle system with cards: pick a character card and drag its action cards onto targets. Built on Turn Battle Base; the battle of Cthangover.",
-  "category": "gameplay",
+  "categories": ["gameplay"],
   "sources": [
     "src/**/*.cs"
   ],