feat(stdlib): new modules + eslint/tsconfig migration

- Add array/async/etc. modules and type tests; migrate to eslint flat config
  and composite tsconfig (vitest typecheck enabled).
- Fix PubSub.emit to snapshot listeners before iterating (stable EventEmitter
  semantics; avoids invoking listeners added during the same emit).

core/stdlib/tsconfig.src.json

@@ -0,0 +1,9 @@
+{
+  "extends": "@robonen/tsconfig/tsconfig.dom.json",
+  "compilerOptions": {
+    "composite": true,
+    "types": [],
+    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.src.tsbuildinfo"
+  },
+  "include": ["src/**/*.ts"]
+}