refactor: convert to ECMAScript where necessary

Also drop @league-of-foundry-developers/foundry-vtt-types.

tsconfig.json

@@ -1,8 +1,9 @@
 {
     "compilerOptions": {
+        "outDir": "dist",
         "target": "ES2021",
         "lib": ["ES2021", "DOM"],
-        "types": ["@league-of-foundry-developers/foundry-vtt-types"],
+        "types": ["@types/jquery", "handlebars"],
         "esModuleInterop": true,
         "moduleResolution": "node",
         "forceConsistentCasingInFileNames": true,
@@ -10,7 +11,9 @@
         "noUncheckedIndexedAccess": true,
         "noImplicitOverride": true,
         "resolveJsonModule": true,
-        "importsNotUsedAsValues": "error"
+        "importsNotUsedAsValues": "error",
+        "checkJs": false,
+        "allowJs": true
     },
-    "include": ["src"]
+    "include": ["src", "client", "common"]
 }