Add typed error taxonomy in errorCodes.ts with public/internal split and i18n message keys

[thlpkee20-wq]

Description

The current errorCodes.ts is ad hoc. Replace it with a typed taxonomy distinguishing public-facing error codes (stable contract) from internal-only ones, and route messages through i18n keys instead of literals.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: src/errors/errorCodes.ts, src/errors/sendError.ts
• Public codes guaranteed to be stable across versions

Suggested execution

• Fork the repo and create a branch
• git checkout -b refactor/error-taxonomy
• Implement changes
  • Discriminated union of public/internal errors
  • Codegen of doc table from taxonomy
  • Type-safe sendError accepting only known codes
• Validate security and correctness assumptions

Test and commit

• Run tests
  • npm test
• Cover edge cases
  • Unknown code at compile-time is a type error
• Include test output and notes

Example commit message

refactor: typed error taxonomy with i18n keys

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[Killerjunior]

@Killerjunior has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I would love to apply for this.

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[drips-wave]

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