feat: configure Deno for ReScript compilation (no Node.js)

Per RSR language policy: Use Deno (not Node.js) for compilation.
- deno task build/clean/watch for ReScript
- Import maps for rescript, @rescript/core, proven
- No node_modules required

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: Test

deno.json

@@ -1,7 +1,16 @@
 {
   "tasks": {
-    "build": "rescript build",
-    "clean": "rescript clean",
-    "watch": "rescript build -w"
+    "build": "deno run -A npm:rescript",
+    "clean": "deno run -A npm:rescript clean",
+    "watch": "deno run -A npm:rescript -w"
+  },
+  "imports": {
+    "rescript": "npm:rescript@^12.1.0",
+    "@rescript/core": "npm:@rescript/core@^1.7.0",
+    "proven/": "../proven/bindings/rescript/src/"
+  },
+  "compilerOptions": {
+    "allowJs": true,
+    "checkJs": false
   }
 }