Add JS toolchain: TypeScript, ESLint, Prettier, Vitest

package.json declares the project as ESM with NodeNext module resolution,
exposing dist/index.js as the library entry and dist/bin/quack.js as the
CLI binary. Dev dependencies are pinned to exact versions (yarn.lock holds
the integrity hashes per repo policy on hash-pinned external references).
Adds a placeholder src/index.ts and a single smoke test so make check is
not a no-op.

package.json

@@ -0,0 +1,39 @@
+{
+    "name": "quack",
+    "version": "0.0.0",
+    "description": "TypeScript client library and CLI for the Ente end-to-end encrypted photo service",
+    "license": "WTFPL",
+    "author": "@sneak <https://sneak.berlin>",
+    "homepage": "https://git.eeqj.de/sneak/quack",
+    "repository": {
+        "type": "git",
+        "url": "https://git.eeqj.de/sneak/quack.git"
+    },
+    "type": "module",
+    "main": "./dist/index.js",
+    "types": "./dist/index.d.ts",
+    "bin": {
+        "quack": "./dist/bin/quack.js"
+    },
+    "files": [
+        "dist/",
+        "README.md",
+        "LICENSE"
+    ],
+    "scripts": {
+        "build": "tsc",
+        "test": "vitest run",
+        "lint": "eslint .",
+        "fmt": "prettier --write .",
+        "fmt-check": "prettier --check ."
+    },
+    "devDependencies": {
+        "@eslint/js": "9.38.0",
+        "@types/node": "22.18.13",
+        "eslint": "9.38.0",
+        "prettier": "3.8.1",
+        "typescript": "5.9.3",
+        "typescript-eslint": "8.46.2",
+        "vitest": "2.1.9"
+    }
+}