feat(setup-npm-registry): browser-assisted classic PAT creation

When no token is found via --token/env/gh CLI, the script now opens
github.com/settings/tokens/new pre-scoped to read:packages with clear
instructions on Note/Expiration/Scopes, falling back to printing the
URL when a browser can't be launched (SSH, containers, CI). Add
--no-open to skip the launch attempt outright.

Also document the flow in README (new 'Generating a GitHub token'
section) and QUICKSTART troubleshooting, and add a hermetic test
covering the --no-open + piped-token path.

package-lock.json

@@ -1,11 +1,11 @@
 {
-  "name": "@redsen/lean-harness",
+  "name": "@redsentech/lean-harness",
   "version": "0.1.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
-      "name": "@redsen/lean-harness",
+      "name": "@redsentech/lean-harness",
       "version": "0.1.0",
       "license": "MIT",
       "dependencies": {