* feat(routing): migrate to AT Protocol-style URLs Change topic URLs from /t/{slug}/{rkey} to /{handle}/{rkey} and profile URLs from /u/{handle} to /profile/{handle}. This aligns with AT Protocol conventions used by Bluesky, Frontpage, and other ecosystem projects, and fixes a latent collision bug where rkey-only lookups could return the wrong topic when two users share an rkey. - Add getTopicUrl (author-scoped) and getReplyUrl helpers in format.ts - Add getTopicByAuthorAndRkey and getReplyByAuthorAndRkey API client methods - Restructure app router: [handle]/[rkey] replaces t/[slug]/[rkey], profile/[handle] replaces u/[handle] - Add reply permalink stub at [handle]/[rkey]/[replyAuthor]/[replyRkey] - Update all components to use new URL patterns - Add authorHandle to SearchResult and SearchSuggestion types - Add subjectAuthorDid/Handle to Notification type - Update mock data, MSW handlers, and all tests - Fix JSON-LD URL bug (was using encodeURIComponent(title)) Depends on: barazo-forum/barazo-api#139 * style(formatting): fix Prettier issues in 4 files * fix(a11y): update pa11y-ci and mobile audit URLs for new route structure