Fix CI: skip env validation for the build + dry-run steps

CI has failed on every push for months at the Build step: `next build` runs the app's
load-time env validation (@t3-oss/env), which throws "Invalid environment variables"
because CI has no ANTHROPIC_API_KEY / DATABASE_URL secrets. The app validates env at
RUNTIME on Vercel, so the build (and the offline dry-run sanity/evals) only need to skip
the load-time check. Set SKIP_ENV_VALIDATION at the job level. Verified locally with no
secrets: build, sanity --dry-run, eval --dry-run (100%), eval:edit --dry-run (10/10) all
pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: DylanMerigaud

.github/workflows/ci.yml

@@ -10,6 +10,11 @@ jobs:
   check:
     name: format · typecheck · lint · knip · test · build · eval
     runs-on: ubuntu-latest
+    # No real secrets in CI: the app validates env at runtime (on Vercel), so the build
+    # and the dry-run sanity/eval only need to skip the load-time env validation. Without
+    # this, `next build` throws "Invalid environment variables" and the job fails.
+    env:
+      SKIP_ENV_VALIDATION: "1"
     steps:
       - uses: actions/checkout@v4