polish: package manifest, README, exclude test files from npm pack

package.json

@@ -1,8 +1,13 @@
 {
   "name": "pi-dev-tools",
   "version": "0.1.0",
+  "description": "Pi extension package that adds formatting-aware edit/write tools plus setup-suggestion tooling for project-local developer workflows.",
   "type": "module",
   "keywords": ["pi-package"],
+  "repository": {
+    "type": "git",
+    "url": "https://gitea.rwiesner.com/pi/pi-dev-tools"
+  },
   "scripts": {
     "test": "tsx --test src/*.test.ts src/**/*.test.ts"
   },