Validate Soroban env vars at build time

[Bryandero98]

Fixes #199.

Adds validateEnv(), called from next.config.ts before build/dev/start, so the app fails fast with a clear, aggregated error instead of silently falling back to demo-mode data or a runtime 500 when config is missing or malformed.

Validates the three variables named in the issue:

• NEXT_PUBLIC_FACTORY_CONTRACT_ID — required, must be a valid Soroban contract id (StrKey.isValidContract, the same check already used in feeBumpGuard.ts).
• NEXT_PUBLIC_SOROBAN_RPC_URL — if set, must be a valid URL (it already has a network-preset fallback, so it isn't required).
• STELLAR_FEE_SPONSOR_SECRET — required and must be a valid Stellar secret key only in server mode, since the /api/sign-fee-bump route it backs doesn't exist under static export.

Repro from the issue, verified locally: with the vars unset, npm run build used to succeed silently in demo mode; with this change it now aborts immediately with:

Invalid environment configuration:
  - NEXT_PUBLIC_FACTORY_CONTRACT_ID is not set.
  - STELLAR_FEE_SPONSOR_SECRET is not set (required in server mode for /api/sign-fee-bump).

With valid values set, next build passes validation and compiles successfully.

Tests

7 new Vitest cases in src/config/validateEnv.test.ts, all green: happy path, missing/invalid value for each variable individually, and the static-export vs. server-mode branch for STELLAR_FEE_SPONSOR_SECRET.

No new dependencies — reuses StrKey from @stellar/stellar-sdk, already a project dependency.

[netlify]

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[netlify]

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[Bryandero98]

Hi team! I noticed this issue was unassigned but had a few folks in the queue. I had some free time and went ahead and implemented the full solution with Vitest coverage (7/7 passing) just to speed things up in case you need a quick merge. I fully respect the Drips Network assignment process, so feel free to review or handle it however fits your workflow best. Cheers!

[Bryandero98]

Following up on the failed deploy previews above.

My validateEnv() from this PR was strict in every context, including Netlify's deploy-preview/branch-deploy builds — which don't necessarily have NEXT_PUBLIC_FACTORY_CONTRACT_ID / STELLAR_FEE_SPONSOR_SECRET configured. Pushed a fix: it now detects Netlify's CONTEXT env var and warns instead of failing the build for deploy-preview/branch-deploy, while staying strict for local dev/build and the production context (the actual intent of this issue). 9/9 tests still green.

But that's not the whole story: I also checked out a clean copy of main with none of my changes and ran next build there directly — it fails too, on a pre-existing TypeScript error in TvlChart.tsx/soroban.ts unrelated to this PR (getPoolHistory's return type is missing [], plus a missing Account import). So the deploy-preview failures above weren't only my env validation — the build breaks downstream of it regardless. Opened #246 with just those two fixes so it's not tangled up with this PR's actual scope, and it also unblocks CI for anyone else's open PR against main, not just this one. There's a third pre-existing issue (useLeaderboard.ts calling getLeaderboard with an unsupported 4th search argument) that's incomplete feature work rather than a typo, so I left that one alone — noted in #246.

[Bryandero98]

Pushed a fix for two pre-existing type errors on this branch (not caused by this PR's env-validation change, but next build type-checks the whole app so they block this branch's own Netlify preview too):

• getPoolHistory's return type was missing the array brackets - the implementation always returns an array.
• Account was used but never imported from @stellar/stellar-sdk.

Same root cause I already fixed separately in #246 (opened against main, since these bugs pre-date this branch and that PR). Applied the identical 2-line fix here directly so this PR isn't blocked waiting on #246 to land first. next build (with CONTEXT=deploy-preview) now passes cleanly, and the full test suite shows no new failures (verified against a clean stash of this commit - same 10 pre-existing failures either way, consistent with flake unrelated to this change).

One remaining caveat I can't fix from here: package-lock.json is out of sync with package.json repo-wide (missing the @next/bundle-analyzer subtree - same finding as in #246), which makes npm ci fail before any build step runs. If Netlify's checks are still red after this push, that's almost certainly why. I didn't regenerate the lockfile myself since I only have npm 11/Node 24 locally and CI's npm ci step (per the public deploy GitHub Actions log) runs npm 10.8.2/Node 20.20.2 - a lockfile regenerated with a newer toolchain than CI's produced a much larger diff than the missing packages alone would explain, and I didn't want to commit that without verifying against the same npm/Node version CI actually uses.

[Bryandero98]

Closing this PR as superseded. Upon checking, issue #199 has already been resolved and merged into main via PR #216 with a warning-only environment validation approach. My implementation is now redundant, so I am closing this out to keep things clean. Great work by the team!