fix: resolve export estimates from preset ids

[gTanusri]

Summary

• Derive export estimate preset dimensions from the canonical PRESETS list
• Replace legacy preset IDs in export estimate tests with current preset IDs
• Add regression coverage to ensure preset IDs do not fall back to custom dimensions

Tests

• npm test -- src\lib\exportEstimate.test.ts could not run because vitest is not installed in this local clone

Closes #1464

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[github-actions]

✅ PR Format Check Passed — @gTanusri

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[vipul674]

@magic-peach Review Reminder.

[magic-peach]

Thanks for opening this! This PR has picked up merge conflicts with main — the codebase has moved a fair amount recently (a Next.js version upgrade and a couple of infra fixes). Rather than leave it conflicting indefinitely, I'm closing it for now. If you'd like to pick "fix: resolve export estimates from preset ids" back up, a fresh rebase (or a new PR off current main) would be very welcome — the idea itself isn't being rejected, just the current diff.