test: add packed npm and pnpm consumer gates

[olliethedev]

Closes #174.

Summary

• pack the current Stack source into clean temporary consumers
• validate minimal core and auth-plus-account fixtures with npm and strict pnpm
• pack Better Auth UI from its maintained repository in CI and require a tarball input locally
• verify direct peers, retained 1.6.16 cohort singleton boundaries, public declarations, and representative Vite production builds
• keep valid implementation-only duplicates such as better-call permitted when the expected version is present

Validation

• harness: 8/8 Vitest tests
• core: npm and pnpm install, typecheck, build
• auth + account with the exact RC4 tarball: npm and pnpm install, cohort evidence, typecheck, build
• lint and diff checks pass
• independent Standards and Spec reviews report no findings

The auth fixture was exercised against the same local 2.0.0-rc.4 source artifact that was subsequently published through trusted publishing; the CI job now repacks Better Auth UI main for every run.

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2 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
better-stack-docs	Ignored		Aug 31, 2026 10:45pm
better-stack-playground	Ignored		Aug 31, 2026 10:45pm

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-31T22:45:06.325212Z	229b64c	PR opened

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