ci: publish @redsentech/lean-harness to GitHub Packages

- Rename npm package scope @redsen -> @redsentech (GitHub Packages
  requires the scope to match the owning org/user login).
- Add publishConfig.registry pointing at npm.pkg.github.com.
- Add .github/workflows/publish.yml: on push of a vX.Y.Z tag (or manual
  dispatch), runs validate + test, checks the tag matches
  package.json's version, then npm publish using the auto-issued
  GITHUB_TOKEN (packages: write permission, no secret to manage).
- Update README/QUICKSTART lh-CLI install instructions for the private,
  org-scoped registry (.npmrc scope + auth token setup).
- Verified locally with npm publish --dry-run: 68 files, correct
  registry target, correct tarball contents.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

package.json

@@ -1,5 +1,5 @@
 {
-  "name": "@redsen/lean-harness",
+  "name": "@redsentech/lean-harness",
   "version": "0.1.0",
   "description": "Imperative, token-lean, self-documenting agent harness for GitHub Copilot CLI and VS Code Copilot.",
   "license": "MIT",
@@ -8,6 +8,9 @@
     "type": "git",
     "url": "git+https://github.com/redsentech/lean-harness.git"
   },
+  "publishConfig": {
+    "registry": "https://npm.pkg.github.com"
+  },
   "type": "module",
   "engines": {
     "node": ">=20"