feat(core): add @choojs/core — ESM port of choo with consolidated nano* internals

Same public API as choo 7.1.0 (use/route/start/mount/toString/emit; choo()
callable with or without new, Choo exported). nanobus, nanorouter+wayfarer,
nanolru+component cache, nanoraf, nanohref, nanotiming, document-ready and
scroll-to-anchor are ported into lib/ with per-file attribution; nanoquery
is replaced by URLSearchParams. The v7 node test suite is ported from tape
to node:test and passes unchanged in behavior.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014NgfSjHE11oFpoSnLVKLXd

packages/core/package.json

@@ -0,0 +1,29 @@
+{
+  "name": "@choojs/core",
+  "version": "8.0.0-dev",
+  "description": "A 4kb framework for creating sturdy frontend applications",
+  "type": "module",
+  "exports": {
+    ".": "./index.js"
+  },
+  "files": [
+    "index.js",
+    "lib"
+  ],
+  "engines": {
+    "node": ">=24"
+  },
+  "dependencies": {
+    "@choojs/html": "*"
+  },
+  "repository": "choojs/choo",
+  "keywords": [
+    "client",
+    "frontend",
+    "framework",
+    "minimal",
+    "composable",
+    "tiny"
+  ],
+  "license": "MIT"
+}