refactor(env): read NODE_ENV through the typed env

[TheKAdhikari]

Summary

constants.ts and store/index.ts read process.env.NODE_ENV directly while the rest of the app already goes through the validated @teispace/env config. This routes them through env.NODE_ENV (the shared group) so the typed, validated env is the single source of truth for runtime config.

Changes

• src/lib/config/constants.ts — isProduction/isDevelopment/isTest now read env.NODE_ENV.
• src/store/index.ts — devTools toggle reads env.NODE_ENV.

next.config.ts's process.env.ANALYZE is intentionally left raw — it's a build-time toggle, not part of the app's runtime env contract.

Test plan

• yarn type-check clean
• yarn lint clean (no new errors)
• yarn test — 149 tests pass

[TheKAdhikari]

⏸️ Blocked on the env publish age gate (resume ~2026-06-21 14:00 UTC).

This PR's CI was failing because @teispace/env@0.2.2 is ESM-only and Next's next.config.ts loader (which now transitively imports the typed env) couldn't require it (ERR_PACKAGE_PATH_NOT_EXPORTED).

That's fixed in @teispace/env@0.2.3 (dual ESM/CJS), published 2026-06-20 13:48 UTC. Verified: a Next 16 app importing @teispace/env/next builds cleanly against 0.2.3.

To land this PR: bump the dep to ^0.2.3 and regenerate the lockfile, then merge. That's blocked right now by Yarn 4.15's npmMinimalAgeGate (1440 min / 24h), which quarantines 0.2.3 until ~2026-06-21 13:48 UTC. After that window, yarn up @teispace/env will resolve it and CI will pass.