Re-offer contribution prep after requested refinements

[hamzamerzic]

Summary

• add a Refine first path to contribution-offer questions
• treat actionable free-text feedback as a deferred decision, then re-offer the revised version after verification
• keep Not now, silence, timeouts, and empty responses non-authorizing

Context

#17 moved contribution offers into question cards with Prepare privately and Not now. It did not distinguish declining preparation from asking to improve the current candidate first. Because the workflow said any non-yes stops, a useful revised contribution could remain local without a new offer.

This follow-up separates prepare, refine, and decline while preserving the safety boundary: feedback never authorizes preparation or publication, and every revised version still needs an explicit Prepare privately response.

Testing

• approval-state contract check passed
• app validation: 0 errors (2 existing CSP warnings)

[hamzamerzic]

Superseded by the reviewed integration in #33, which preserves this PR's commits and authorship. Thank you — the combined change is now on main.