Implement an Async Chain, to enable async chain operations

.gitignore

@@ -1,3 +1,7 @@
 build/
 node_modules/
 .eslintcache
+
+.junie/
+.turbo/
+.env

AGENTS.md

@@ -0,0 +1 @@
+CLAUDE.md

CLAUDE.md

@@ -0,0 +1,46 @@
+# CLAUDE.md
+
+## Project Overview
+
+`@opencreek/ext` is a TypeScript utility library providing functional collection processing, async chain support, and various utilities.
+
+## Commands
+
+```bash
+# Build
+pnpm run build      # compiles TypeScript → build/
+
+# Test
+pnpm test           # runs AVA tests (src/**/*.test.ts)
+
+# Lint
+pnpm run lint       # check with Prettier + ESLint
+pnpm run lint:fix   # auto-fix issues
+```
+
+## Key Structure
+
+```
+src/
+  index.ts                    # barrel export
+  collections.ts              # Chain<T>, ObjectChain<K,T>
+  collections/
+    AsyncChain.ts             # AsyncChain<T>, AsyncObjectChain<K,T>
+  BigDecimal.ts               # high-precision decimal arithmetic
+  StopWatch.ts                # performance timing
+  error.ts, raise.ts          # error utilities
+  strings.ts                  # string/output helpers
+  range.ts, sleep.ts, parseNumber.ts, objects.ts, table.ts, todo.ts
+build/                        # compiled output (generated)
+```
+
+## Code Style
+
+- No semicolons (Prettier config: `"semi": false`)
+- Strict TypeScript (ES2020 target, CommonJS modules)
+- ESLint with max-warnings=0
+- Tests use AVA framework with ts-node
+
+## Package Manager
+
+Use `pnpm` (not npm or yarn).

package.json

@@ -26,16 +26,16 @@
   "devDependencies": {
     "@eslint/eslintrc": "^3.3.1",
     "@eslint/js": "^9.32.0",
-    "@types/node": "^24.2.0",
     "@typescript-eslint/eslint-plugin": "^8.38.0",
     "@typescript-eslint/parser": "^8.38.0",
     "auto": "^11.3.0",
     "ava": "^6.4.1",
     "eslint": "^9.0.0",
     "eslint-config-prettier": "^10.1.8",
     "prettier": "^3.6.2",
-    "ts-node": "^10.9.2",
-    "typescript": "5.8.3"
+    "typescript": "5.9.2",
+    "@types/node": "^24.2.0",
+    "ts-node": "^10.9.2"
   },
   "prettier": {
     "semi": false