feat(ui): one answer trail for every step flow - #2576

🟢 Confidence 9/10 · safe to merge. Contained CSS fix in one kit view; the shrink chain that makes the ellipsis appear is verified by reading the classes, and the truncation itself has no test.
_{no findings · tests partial −1 · risk medium}

Replaces five hand-rolled step trails with one kit answerTrail; the last commit lets a long answer ellipsize inside its receipt chip instead of pushing the trail past a phone's width. Safe to merge.

• answerTrail replaces stepTrail and the hand-rolled trails in connect pages, onboarding, GCP and status page dialogs
• A done chip renders its answer in a truncate span, with the check icon shrink-0
• maple/one-step-trail confines aria-current="step" to the kit

_{67b267c · Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}