Add showSeasonZero checkbox in settings panel with toggle styling (42x23px switch, green when active). Implement applySeasonZeroPreference() to filter S00E episodes via .season-zero-hidden class and hide empty series with .season-zero-empty. Update missing count in nav badge and stats to exclude hidden season zero episodes. Add dynamic hint text toggle between "eingeblendet"/"ausgeblendet". Remove season zero exclusion from is_german_review_candidate() in app.py to