Make Kith onboarding replayable and illustrated

[sarthakagrawal927]

Summary

• add a hand-drawn remembered-moment illustration to first-run onboarding
• expose Replay onboarding from the Connection screen
• keep replay non-destructive so it cannot create a duplicate person or note
• preserve the real person-and-memory activation flow for first launch

Verification

• KithOnboardingReplayTests: 1 passed, 0 failed
• simulator visual proof on iPhone 17 Pro / iOS 26.4
• git diff --check

Tracks Significant-Hobbies/significanthobbies#145.

Illustration style derived from Ian Xiaohei Illustrations by Ian, revision 91b560.