chore(database): remove unused EbookNote backward compatibility functions

- Remove CreateEbookNote, UpdateEbookNote, DeleteEbookNote queries
- These were marked as backward compatibility but never used
- API uses CreateMediaNote, UpdateMediaNote, DeleteMediaNote instead
- Remove misleading backward compatibility comments
- Regenerate sqlc code

internal/database/queries/queries.sql

@@ -470,23 +470,6 @@ RETURNING *;
 -- name: DeleteMediaHighlight :exec
 DELETE FROM media_highlights WHERE id = $1;
 
--- Backward compatibility - Ebook Notes queries (using views)
--- name: CreateEbookNote :one
-INSERT INTO media_notes (media_item_id, user_id, content, position)
-VALUES ($1, $2, $3, $4)
-RETURNING *;
-
--- name: UpdateEbookNote :one
-UPDATE media_notes SET
-    content = $2,
-    position = $3,
-    updated_at = NOW()
-WHERE id = $1
-RETURNING *;
-
--- name: DeleteEbookNote :exec
-DELETE FROM media_notes WHERE id = $1;
-
 -- Refresh Tokens queries
 -- name: CreateRefreshToken :one
 INSERT INTO refresh_tokens (user_id, token, expires_at)