docs(install): add empty-folder verify steps for v0.8.0 install paths

docs/how-to/install-claude-plugin.md

@@ -96,6 +96,43 @@ From a Claude Code session with the plugin installed, list the marketplace and c
 
 Contributors with a local checkout can smoke-test the plugin directly without going through marketplace install — see Option B above. The smoke-test requires `npm run build:claude-plugin` first because the bundle is gitignored on `develop`/`main`.
 
+### End-to-end test in an empty folder
+
+After installing on a fresh machine — or any time you want to confirm both install paths resolve against the published release — run both checks in an empty directory. Each path exercises an independent half of the v0.8.0 surface ([ADR-0040](../adr/0040-migrate-npm-publication-to-npmjs-com.md) + [ADR-0043](../adr/0043-distribute-claude-plugin-bundle-from-orphan-dist-branch.md) + ADR-0044 — see [main](https://github.com/Luis85/agentic-workflow/blob/main/docs/adr/0044-restore-npmjs-trusted-publishing.md) until the develop backmerge lands).
+
+**1. CLI install (npm package).**
+
+```bash
+mkdir specorator-test && cd specorator-test
+npm install -g specorator
+specorator --version            # → "specorator v0.8.0" (or current)
+specorator init --dry-run       # → install report, no files written
+specorator init                 # → seeds project shell; existing files skipped
+```
+
+Sanity-check that the published package carries a sigstore provenance attestation:
+
+```bash
+npm view specorator dist.attestations
+# { url: '.../-/npm/v1/attestations/specorator@<version>',
+#   provenance: { predicateType: 'https://slsa.dev/provenance/v1' } }
+```
+
+**2. Claude Code plugin install (marketplace + orphan dist branch).**
+
+Open Claude Code in the same empty folder, then in the session:
+
+```text
+/plugin marketplace add Luis85/agentic-workflow
+/plugin install specorator@specorator-marketplace
+/reload-plugins
+/specorator:welcome
+```
+
+This is the end-to-end test for the orphan `dist/claude-plugin` branch. Claude Code reads `.claude-plugin/marketplace.json` from `main`, sees the `git-subdir` source pinned to `dist/claude-plugin`, sparse-clones that branch, and loads `claude-plugin/specorator/` from the CI-built tree. A green `/specorator:welcome` confirms the orphan-branch distribution is functional.
+
+If you've installed Specorator on this machine before, run `/plugin marketplace update` first so Claude Code re-resolves the marketplace source.
+
 ## Plugin vs project files
 
 The plugin makes Specorator's reusable Claude layer available. It does not automatically copy project-local workflow files into the folder you opened during installation, and Claude Code does not currently expose a documented plugin post-install hook for running project setup automatically.