Validate and bound config request inputs against malformed payloads

[mikewheeleer]

Harden config input validation

Description

The config endpoints accept request bodies with limited validation, risking malformed or oversized inputs reaching the store. This issue adds strict input validation.

Requirements and context

• Repository scope: StableRoute-Org/Stableroute-backend only.
• Reject unknown fields, wrong types, and out-of-range values on config writes with a structured 400.
• Bound string lengths and numeric ranges; return a machine-readable error code.
• Cover the validation in tests.

Suggested execution

• Fork the repo and create a branch
• git checkout -b feature/config-02-validation
• Implement changes
  • Write code in: the relevant module.
  • Write comprehensive tests in: cover the new behaviour and edge cases.
• Test and commit

Test and commit

• Run npm run lint, npm test, and npm run build.
• Cover edge cases: missing field, wrong type, oversized string, boundary numbers.
• Include the full test output in the PR description.

Example commit message

feat(config): validate and bound request inputs

Guidelines

• Minimum 95 percent test coverage for impacted modules.
• Clear, reviewer-focused documentation.
• Timeframe: 96 hours.

Community & contribution rewards

• 💬 Join the StableRoute community on Discord: https://discord.gg/37aCpusvx
• ⭐ This is a GrantFox OSS / Official Campaign task and may be rewarded. When your PR is merged you'll be prompted to rate the project — a 5-star rating is much appreciated.