Feat: Implements Job registry and get bids view function

[devfoma]

Summary

This pr closes #83

• Implemented production-ready get_job and get_bids view functions in the JobRegistry contract with graceful error handling.
• Transitioned get_job and get_bids to return Result<T, JobRegistryError>, replacing panics and minimal defaults with standard Soroban error codes.
• Updated the Reputation contract's cross-contract invocation logic to maintain compatibility with the new JobRegistry return types.
• Provided comprehensive technical documentation for the new view functions in the /docs folder and internal docstrings.

Testing

• Unit tests updated across job_registry to handle Result types and ensure 90%+ coverage.
• New test cases added to verify JobNotFound error states for both get_job and get_bids.
• Cross-contract call logic verified via code review in the reputation contract.

Checklist

• Linked issue or backlog item (Implement JobRegistry::get_job and get_bids view functions)
• Contract behavior and invariants are described clearly
• Docs updated if contract interfaces or workflows changed
• Scope stays limited to one contract concern (View function implementation)

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