Sync ERROR_CODES catalogue with contract enums

[greatest0fallt1me]

Summary

ERROR_CODES.md covers vault and some others, but lists vault variants that are never emitted (e.g. InitialBalanceExceedsOnLedger) and omits fee, refund, rescue, batch_claim and registry enums.

Why this matters

Clients map numeric codes to messages from this document; missing or phantom entries produce wrong error messages in the UI.

Scope

Generate the tables from each #[contracterror] enum (small script), mark unused codes as reserved, and add a CI diff check.

Relevant code in CalloraOrg/Callora-Contracts:

• docs/ERROR_CODES.md
• contracts/vault/src/errors.rs
• contracts/settlement/src/errors.rs
• contracts/refund/src/errors.rs

Priority

Low

Acceptance criteria

• Every contract error enum represented
• Unused variants marked reserved
• CI fails when enums and doc diverge
• Script used for generation is committed under scripts/

Validation

cargo test --workspace err_stab

Non-goals

• Typo-only, formatting-only, or cosmetic changes.
• Unrelated refactors, dependency upgrades, or broad rewrites.
• Removing safeguards or weakening validation to make tests pass.

Contributor application

Before coding, describe the affected modules, proposed state/invariant changes, test strategy, compatibility considerations, and an estimate. Wait for assignment before starting implementation.

PR requirements

Use a feature branch and include Closes #<issue-number>. Address every criterion, map criteria to code and tests, explain security and failure-mode handling, and ensure CI passes.

Quality review

A maintainer will assess correctness, completeness, test depth, compatibility, observability, and adverse-case handling. A substantive implementation is required; merge or CI status alone does not guarantee reward eligibility.

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Generated by Claude Code

[AkpakaProsper]

@AkpakaProsper has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hi Maintainer, i have reviewed the issue and I'm confident that I can solve it, please assign.Thank You

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