feat: apply web of trust filter to thread replies

[barrydeen]

Summary

• WoT filter already silently drops events at EventRepository.addEvent and inside NotificationRepository, but thread replies bypassed both paths — ThreadViewModel keeps its own threadEvents map seeded via cacheEvent() and getCachedThreadEvents(), neither of which checks WoT
• Apply isWotFiltered inside rebuildTree() alongside the existing block / mute / spam filters
• Root note stays visible (user explicitly navigated to it); replies from authors outside the qualified network are silently dropped, matching feed + notifications behavior
• isWotFiltered changed from private to package-default so ThreadViewModel can reuse the same logic instead of duplicating it
• WOT_EXEMPT_KINDS already excludes the relevant infrastructure kinds (0/3/4/10002/10050/1059/13/14); kind 1 replies are not exempt, which is what we want

Test plan

• With WoT disabled: open a thread with replies — all replies render as before
• With WoT enabled and graph computed: open a thread containing replies from accounts outside your qualified network — those replies are hidden; replies from follows and qualified second-degree accounts remain
• Open a thread whose root author is outside your network — root still renders (you tapped in deliberately)
• With WoT enabled but graph not yet computed: replies are not filtered (isNetworkReady returns false) — falls open, no regression
• Confirm own replies in a thread are never filtered (currentUserPubkey carve-out in isWotFiltered)