The /follow route now accepts naddr1 identifiers for follow packs
(kind 39089) and follow sets (kind 30000) in addition to npub/nprofile.
Renders an immersive fullscreen layout with pack info hero, avatar
stack, big Follow All CTA with status indicator, and Feed/Members
tabs using the standard SubHeaderBar arc.
Follow All uses the safe fetch-fresh -> modify -> publish pattern
with prev for published_at preservation.
Shared components (PackFeedTab, MemberCard, MemberCardSkeleton) and
parsePackEvent are reused from FollowPackDetailContent and packUtils.
Also fixes SubHeaderBar tab indicator positioning when innerClassName
centers the tab container (adds containerOffset + ResizeObserver for
layout-dependent recalculation).