UI: Local Validation Bridge for Web UI (Developer Mode)

[szverev]

Summary

Enable the web UI to run validation locally in a developer-friendly way by introducing a local execution bridge (since browsers cannot spawn local processes).

Notes

Implementation choice left to contributor, but must be deterministic and simple to run:

• a small local HTTP wrapper around the validator, or
• another minimal bridging mechanism documented clearly

Requirements / Invariants

• Must return canonical { exitCode, errors[] }
• Must not change semantics or post-process errors beyond deterministic formatting

Acceptance Criteria

• UI can run validation using local graph + rules inputs and receive canonical output
• Setup is documented and reproducible