[oracle] Audit the zod v3 to v4 migration

[Otaiki1]

Summary

Dependabot bumped zod from 3.25 to 4.4 in the oracle (PR #1035) with CI disabled, so no automated signal verified it. zod 4 has breaking changes (error API, .default behavior, stricter coercion) that can silently change config validation in oracle/src/config.

What to do

• Build and run the oracle test suite; fix any compile/runtime breaks from zod 4.
• Review every schema for v4 semantic changes (error.issues shape, z.record args, coercion) against the migration guide.
• Add a config-parsing test locking in current expected behavior.

Acceptance criteria

• Oracle builds and tests pass on zod 4; config validation behavior explicitly asserted.

[Niffy03]

@Niffy03 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi again, i can take care of this within the hour once assigned.

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[esenyidaniel-hash]

@esenyidaniel-hash has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Please can I work on this?

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[drips-wave]

Congratulations, @esenyidaniel-hash! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

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