Harden release flow with registry verification and dist-tag checks (#4800)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - Paperclip is distributed as npm packages, including plugins like
`plugin-e2b`
> - The release process publishes canary and stable builds via npm
dist-tags
> - But there was no automated verification that published packages
actually landed with the correct dist-tags, and broken canary publishes
could silently ship to users
> - This PR adds a registry verification script that checks published
packages match their expected dist-tags, and wires it into PR CI so
regressions are caught before merge
> - The benefit is release integrity is verified automatically, and
broken dist-tag states are caught early

## What Changed

- Added `scripts/verify-release-registry-state.mjs` — verifies that
published npm packages have correct dist-tag assignments and detects
orphaned or mispointed tags
- Added `scripts/verify-release-registry-state.test.mjs` — test coverage
for the verification logic
- Updated `scripts/release.sh` to include canary dist-tag safety checks
before publishing
- Updated `.github/workflows/pr.yml` to run registry verification as a
CI step
- Updated `doc/PUBLISHING.md` and `doc/RELEASING.md` with the new
verification workflow

## Verification

- `pnpm test` — all tests pass including new verification script tests
- `node scripts/verify-release-registry-state.mjs` — runs against the
live npm registry and reports current state
- CI: the new PR workflow step runs on every PR push

## Risks

- Low risk. This is additive CI and tooling — no runtime code changes.
The registry verification is read-only (queries npm, does not publish).
The release script changes add safety checks that abort before
publishing if state is unexpected.

## Model Used

Codex GPT 5.4 high via Paperclip.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [ ] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

doc/PUBLISHING.md

@@ -143,6 +143,13 @@ This keeps the default install path unchanged while allowing explicit installs w
 npx paperclipai@canary onboard
 ```
 
+The release script now verifies two things after a canary publish:
+
+- the `canary` dist-tag resolves to the version that was just published
+- every published internal `@paperclipai/*` dependency referenced by that manifest exists on npm
+
+It also treats `latest -> canary` as a failure by default, because npm metadata can otherwise leave the default install path pointing at an unreleased canary dependency graph. Only pass `./scripts/release.sh canary --allow-canary-latest` when that `latest` behavior is explicitly intended.
+
 ### Stable
 
 Stable publishes use the npm dist-tag `latest`.