fix(migrations): renumber feed-view migration 006 → 010

The new v_feed-rewrite migration collided with the existing 006_user_pin_lockout
(versions must be unique). Verified against a fresh Postgres: all migrations
001–010 now apply cleanly on startup.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/migrations/010_feed_view_perf.down.sql

@@ -0,0 +1,23 @@
+-- Restore the original join-based v_feed definition.
+CREATE OR REPLACE VIEW v_feed AS
+SELECT
+    u.id,
+    u.event_id,
+    u.user_id,
+    usr.display_name             AS uploader_name,
+    usr.is_banned,
+    usr.uploads_hidden,
+    u.preview_path,
+    u.thumbnail_path,
+    u.mime_type,
+    u.caption,
+    u.created_at,
+    COUNT(DISTINCT l.user_id)    AS like_count,
+    COUNT(DISTINCT c.id)         AS comment_count
+FROM upload u
+JOIN "user" usr ON u.user_id = usr.id
+LEFT JOIN "like" l  ON l.upload_id = u.id
+LEFT JOIN comment c ON c.upload_id = u.id AND c.deleted_at IS NULL
+WHERE u.deleted_at IS NULL
+  AND usr.uploads_hidden = FALSE
+GROUP BY u.id, usr.display_name, usr.is_banned, usr.uploads_hidden;