Refactor media management.

- Change tiled UI to table UI.
- Add support for search and pagination.
- Important: This breaks the `GET /api/media` API to introduce pagination
  fields. Media items are now moved into `{ data: results[] }`.

schema.sql

@@ -164,6 +164,7 @@ CREATE TABLE campaign_media (
 DROP INDEX IF EXISTS idx_camp_media_id; CREATE UNIQUE INDEX idx_camp_media_id ON campaign_media (campaign_id, media_id);
 DROP INDEX IF EXISTS idx_camp_media_camp_id; CREATE INDEX idx_camp_media_camp_id ON campaign_media(campaign_id);
 
+
 -- links
 DROP TABLE IF EXISTS links CASCADE;
 CREATE TABLE links (