fix: update platform support docs for cross-runtime compatibility

- README: Node.js 18+ → Node.js 18+, Deno, and Bun
- package.json: add deno:true field
- build-distribution.md: consolidate engine/platform sections

deno.lock

@@ -33,6 +33,7 @@
     ],
     "packageJson": {
       "dependencies": [
+        "npm:@alkdev/pubsub@0.1",
         "npm:@alkdev/typebox@~0.34.49",
         "npm:@preact/signals-core@^1.14.1",
         "npm:@types/node@22",