[CT-70] hash_validator.rs has no test for non-UTF8/binary input

[mftee]

Overview

contract/src/hash_validator.rs validates submitted hash strings (feeding CT's SHA-256/SHA-512 support), but has no evident test for malformed binary or non-UTF8 byte sequences arriving in the hash field — worth confirming the Axum extractor/validator rejects this cleanly rather than panicking.

Tasks

• Add a test submitting invalid UTF-8 bytes in the hash field and assert a clean 4xx response, not a panic or 500
• Add a test for a hash string of unexpected length (too short/too long for both SHA-256 and SHA-512)

Acceptance Criteria

• Non-UTF8 or wrong-length input to the hash field never panics the service and always returns a clean validation error

Notes for Contributors

Comment below to be assigned.

[shaarknado]

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I could love to work on this issue

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[samlogy1]

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please can you kindly assign this issue to me

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[ohamamarachi474-del]

@ohamamarachi474-del has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

can i work on this issue ???

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@ohamamarachi474-del's PR #1243 was approved and merged by @mftee.

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