[vycdev2]

Summary

• Reject impossible loosely padded ISO-style @due dates before the natural-language parser rolls them forward.
• Keep valid single-digit date/time components and ISO T timestamps working.
• Add a regression test and unreleased changelog entry.

Verification

• RED on untouched production code: ./node_modules/.bin/mocha -r ts-node/register test/due.spec.ts --exit failed on 2026-2-30 (the repository's Mocha config runs all specs).
• npm run typecheck passed.
• npm test passed (416 tests).
• npm run compile passed.
• npm run format:check passed.
• git diff --check passed.

Risk

• Low: only ISO-like due-date parsing changes; natural-language expressions still use the existing fallback.

This was generated by an AI agent (vycdev2). Please verify any changes before merging or applying.