ci: speed up PR verify workflow (#6137)

## Thinking Path

> - Paperclip orchestrates AI agents through a control-plane repo that
relies on GitHub Actions as part of its release and verification safety
net.
> - The PR workflow in `.github/workflows/pr.yml` is the core CI path
protecting pull requests before merge.
> - Baseline measurement work in [PAPA-335](/PAPA/issues/PAPA-335)
showed the old single `verify` job was the critical-path bottleneck,
with general tests and build serialized together.
> - Follow-up implementation in [PAPA-338](/PAPA/issues/PAPA-338) and
[PAPA-339](/PAPA/issues/PAPA-339) split that work into parallel lanes
and removed redundant clean-runner prebuild work.
> - [PAPA-340](/PAPA/issues/PAPA-340) now needs real post-change PR
workflow evidence, not local inference, to compare against the May 15,
2026 baseline and decide whether phase-2 work is still justified.
> - This pull request publishes the already-implemented CI speedup
branch so GitHub can run the actual `PR` workflow against it.
> - The benefit is that CI timing decisions are based on measured runs
from the exact workflow shape we intend to ship.

## What Changed

- Split the PR workflow so `policy` fans out into separate `Typecheck +
Release Registry`, grouped `General tests`, and `Build` jobs.
- Kept the serialized server matrix, canary dry run, and e2e jobs intact
while removing the old monolithic `verify` bottleneck.
- Reworked grouped general-test execution in
`scripts/run-vitest-stable.mjs` so the workflow can run balanced
non-serialized lanes.
- Replaced redundant clean-runner prebuild gates with the idempotent
`ensure-build-deps` path used by the relevant CI entrypoints.

## Verification

- `ruby -e "require 'yaml'; YAML.load_file('.github/workflows/pr.yml');
puts 'yaml-ok'"`
- `node scripts/run-vitest-stable.mjs --mode general --dry-run`
- `node scripts/run-vitest-stable.mjs --mode general --group
general-server --dry-run`
- `node scripts/run-vitest-stable.mjs --mode general --group
general-workspaces-a --dry-run`
- `node scripts/run-vitest-stable.mjs --mode general --group
general-workspaces-b --dry-run`
- `pnpm test:run:general -- --group general-workspaces-b`
- `pnpm test:run:general -- --group general-workspaces-a`
- `pnpm test:run:general -- --group general-server`
- `pnpm run typecheck:build-gaps`
- `pnpm --filter @paperclipai/plugin-hello-world-example typecheck`

## Risks

- Required-check and branch-protection settings may still reference the
old single `verify` job name.
- Parallel CI lanes can expose hidden ordering assumptions or
clean-runner bootstrap gaps that local grouped dry-runs did not surface.
- Because the branch is behind current `master`, merge conflicts or
unrelated upstream drift could affect the measured runtime until the
branch is rebased.

> Checked `ROADMAP.md`; this work is CI throughput maintenance for the
existing PR verification path, not duplicate feature work.

## Model Used

- OpenAI Codex via Paperclip `codex_local`, GPT-5-class coding agent
with repository read/write, shell execution, and GitHub CLI/tool use.
The runtime does not expose a more specific backend model ID in-session.

## 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
- [ ] 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

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

package.json

@@ -19,8 +19,8 @@
     "test": "pnpm run test:run",
     "test:watch": "pnpm run preflight:workspace-links && vitest",
     "test:run": "pnpm run preflight:workspace-links && node scripts/run-vitest-stable.mjs",
-    "test:run:general": "pnpm run preflight:workspace-links && pnpm --filter @paperclipai/plugin-sdk build && node scripts/run-vitest-stable.mjs --mode general",
-    "test:run:serialized": "pnpm run preflight:workspace-links && pnpm --filter @paperclipai/plugin-sdk build && node scripts/run-vitest-stable.mjs --mode serialized",
+    "test:run:general": "pnpm run preflight:workspace-links && pnpm --filter @paperclipai/plugin-sdk ensure-build-deps && node scripts/run-vitest-stable.mjs --mode general",
+    "test:run:serialized": "pnpm run preflight:workspace-links && pnpm --filter @paperclipai/plugin-sdk ensure-build-deps && node scripts/run-vitest-stable.mjs --mode serialized",
     "db:generate": "pnpm --filter @paperclipai/db generate",
     "db:migrate": "pnpm --filter @paperclipai/db migrate",
     "issue-references:backfill": "pnpm run preflight:workspace-links && tsx scripts/backfill-issue-reference-mentions.ts",