dep: replace EOL @vercel/kv with @upstash/redis

[kotakanbe]

Problem

@vercel/kv is EOL-Confirmed — it has been deprecated in favor of @upstash/redis, which it was a thin wrapper around. Continuing to depend on an EOL package means no bug fixes, no security patches, and potential supply chain risk.

Detected by uzomuzo diet — a dependency removability analyzer.

Impact analysis

• Files: 5 files import this dependency
• Call sites: 7 calls across 5 APIs
• Exclusive transitive deps: 2 (removed together with @vercel/kv)
• Stays as indirect: No — full removal from the dependency tree
• Difficulty: moderate

Usage breakdown

File	Usage	Category
run-tests.js	createClient → get/set for test timings	CI infrastructure
.github/actions/next-stats-action/src/add-comment.js	createClient → lrange/rpush/ltrim for stats history	CI infrastructure
.github/actions/upload-turboyet-data/src/main.js	createClient → rpush/set for turboyet data	CI infrastructure
examples/with-redis/app/actions.tsx	kv.hset, kv.zadd, kv.sadd	Example code
examples/with-redis/app/page.tsx	kv.zrange, kv.multi, kv.hgetall	Example code

Proposed replacement

@upstash/redis — the upstream library that @vercel/kv wrapped. All Redis commands are 1:1 compatible.

API mapping

@vercel/kv	@upstash/redis
createClient({ url, token })	new Redis({ url, token })
import { kv } (auto-env)	Redis.fromEnv()
All Redis commands (get, set, rpush, hset, zadd, zrange, multi, etc.)	Identical

Environment variable changes

• CI infrastructure (run-tests.js, actions): Uses explicit { url, token } constructor — no env var changes needed
• examples/with-redis: Redis.fromEnv() reads UPSTASH_REDIS_REST_URL / UPSTASH_REDIS_REST_TOKEN instead of KV_REST_API_URL / KV_REST_API_TOKEN

Notes

• upload-turboyet-data has a bundled dist/index.js that needs rebuilding after the source change
• 4 package.json files reference @vercel/kv: root, next-stats-action, upload-turboyet-data, examples/with-redis
• No API leakage — all usage is internal
• No build tags or generated code involved
• Happy to submit a PR if this direction looks good