feat(audiobooks): migrations 154 + 155 for Phase 1 close-out

154 adds hide_from_continue to user_watch_progress (backs the
ABS remove/readd-to-continue-listening endpoints). 155 creates
abs_rss_feeds for the upcoming RSS surface.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

migrations/154_user_watch_progress_hide_from_continue.down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE public.user_watch_progress
+    DROP COLUMN IF EXISTS hide_from_continue;