fix: declare fastify as a peer dependency

[ezefernandezyf]

Fixes #262

Summary

The published type declarations (dist/cjs/index.d.ts) import types from fastify, but fastify was not declared in peerDependencies. In pnpm-strict (non-hoisted) setups this breaks type resolution with TS2307: Cannot find module 'fastify' plus a TS2344 cascade (TypeBoxTypeProvider does not satisfy FastifyTypeProvider).

Declare "fastify": "^5.0.0" as a flat required peer dependency, matching the repo's devDependencies range and the ecosystem convention.

Changes

File	Change
package.json	Add fastify: ^5.0.0 to peerDependencies
.github/workflows/ci.yml	Add consumer-types job: pack the real tarball, install under pnpm strict as a workspace member, tsc --noEmit on a README-faithful consumer

Verification

• npm test: attw all resolutions green, 11/11 node tests, 20/20 tstyche assertions
• npm run lint: clean
• Consumer proof (WITH peer): tsc --noEmit exit 0, fastify symlinked into the plugin's node_modules
• Consumer proof (WITHOUT peer, pre-fix): exit 2, TS2307 + TS2344 (the exact issue Fastify().withTypeProvider<T> is incompatible with the latest fastify (5.6.2) #262 signature)

Why the CI check matters

attw and tstyche cannot detect a missing peer dependency: neither exercises consumer-side peer resolution. The consumer-types job installs the published tarball exactly like a strict pnpm consumer and type-checks it, which is the only check that proves this fix. The fixture is a pnpm workspace member (a plain file: dir masks the defect via hoisting), strips devDependencies from the extracted manifest (real consumers never install a dependency's devDeps), and pins @types/node@^24 (@types/node@26 breaks thread-stream under skipLibCheck: false).

Note for maintainers (out of scope)

The automerge job gates Dependabot PRs on needs: [quality-check, test] only; adding consumer-types to that list would also gate Dependabot PRs on the new check.

[Fdawgs]

Thanks for the PR, unfortunately this'll be a no.
See fastify/fastify-sensible#216 (comment)

[ezefernandezyf]

Thanks for the quick review @Fdawgs, understood. I had missed the ecosystem decision in fastify/fastify#1780 and fastify-plugin#93 that plugins intentionally do not declare fastify as a peer dependency. Closing this PR. Appreciate the pointer!