Capture wizard — 3-step / 4-step adaptive flow

Popup wizard restructure: Extract → (AI Boost?) → Upload → Result. Dynamic step count based on whether AI Boost is enabled. AI step output flows back to extract-done for review before [Confirm save] / [Re-run AI].

Sticky action button at panel bottom stays visible when content scrolls. Confetti on commit success (3-color brand palette).

Released across v0.4.0 and v0.6.0.