fix: use correct JSON Schema keyword in getSignedURLs response

[oniani1]

Closes #1023

The error property in the getSignedURLs response schema uses error: as the JSON Schema keyword instead of type:. This isn't a valid JSON Schema keyword, so @fastify/swagger skips it when generating the OpenAPI spec -- the published API has no type info for this field.

The sibling signedURL property in the same object already uses type: ['string', 'null'] correctly. One-word fix to match.

[coveralls]

Coverage Report for CI Build 24474844911

Coverage decreased (-3.4%) to 79.064%

Details

• Coverage decreased (-3.4%) from the base build.
• Patch coverage: 1 of 1 lines across 1 file are fully covered (100%).
• 4301 coverage regressions across 99 files.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

4301 previously-covered lines in 99 files lost coverage.

Top 10 Files by Coverage Loss	Lines Losing Coverage	Coverage
src/internal/database/migrations/migrate.ts	291	52.25%
src/internal/queue/queue.ts	257	10.77%
src/internal/streams/hash-stream.ts	191	26.22%
src/internal/concurrency/async-abort-controller.ts	180	17.11%
src/storage/protocols/iceberg/catalog/reconciler.ts	172	13.38%
src/storage/protocols/iceberg/catalog/rest-catalog-client.ts	161	65.52%
src/internal/database/pool.ts	145	65.05%
src/storage/protocols/iceberg/knex.ts	132	64.65%
src/internal/errors/codes.ts	128	73.79%
src/storage/events/upgrades/sync-catalog-ids.ts	124	10.61%

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Coverage Stats

Relevant Lines:	37897
Covered Lines:	30111
Line Coverage:	79.45%
Relevant Branches:	4026
Covered Branches:	3035
Branch Coverage:	75.38%
Branches in Coverage %:	Yes
Coverage Strength:	311.78 hits per line

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💛 - Coveralls