feat: update database queries for multiple folder management

- Replace single folder queries with multiple folder operations
- Add AddUserEbookFolder, GetUserEbookFolders, DeleteUserEbookFolder queries
- Regenerate Go code with sqlc
- Update models to include UserEbookFolders struct

backend/internal/database/queries.sql.go

@@ -11,6 +11,27 @@ import (
 	"github.com/jackc/pgx/v5/pgtype"
 )
 
+const AddUserEbookFolder = `-- name: AddUserEbookFolder :one
+INSERT INTO user_ebook_folders (user_id, folder_path) VALUES ($1, $2) RETURNING id, user_id, folder_path, created_at
+`
+
+type AddUserEbookFolderParams struct {
+	UserID     pgtype.UUID `db:"user_id" json:"user_id"`
+	FolderPath string      `db:"folder_path" json:"folder_path"`
+}
+
+func (q *Queries) AddUserEbookFolder(ctx context.Context, arg AddUserEbookFolderParams) (UserEbookFolders, error) {
+	row := q.db.QueryRow(ctx, AddUserEbookFolder, arg.UserID, arg.FolderPath)
+	var i UserEbookFolders
+	err := row.Scan(
+		&i.ID,
+		&i.UserID,
+		&i.FolderPath,
+		&i.CreatedAt,
+	)
+	return i, err
+}
+
 const CreateEbook = `-- name: CreateEbook :one
 INSERT INTO ebooks (title, author, isbn, description, file_path, file_size, mime_type, cover_image_path, series, series_number, tags, asin, date_published, publisher, contributors)
 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15)
@@ -177,6 +198,20 @@ func (q *Queries) DeleteReadingProgress(ctx context.Context, arg DeleteReadingPr
 	return err
 }
 
+const DeleteUserEbookFolder = `-- name: DeleteUserEbookFolder :exec
+DELETE FROM user_ebook_folders WHERE user_id = $1 AND folder_path = $2
+`
+
+type DeleteUserEbookFolderParams struct {
+	UserID     pgtype.UUID `db:"user_id" json:"user_id"`
+	FolderPath string      `db:"folder_path" json:"folder_path"`
+}
+
+func (q *Queries) DeleteUserEbookFolder(ctx context.Context, arg DeleteUserEbookFolderParams) error {
+	_, err := q.db.Exec(ctx, DeleteUserEbookFolder, arg.UserID, arg.FolderPath)
+	return err
+}
+
 const GetEbook = `-- name: GetEbook :one
 SELECT id, title, author, isbn, description, file_path, file_size, mime_type, cover_image_path, created_at, updated_at, series, series_number, tags, asin, date_published, publisher, contributors FROM ebooks WHERE id = $1
 `
@@ -207,6 +242,36 @@ func (q *Queries) GetEbook(ctx context.Context, id pgtype.UUID) (Ebooks, error)
 	return i, err
 }
 
+const GetEbookByFilePath = `-- name: GetEbookByFilePath :one
+SELECT id, title, author, isbn, description, file_path, file_size, mime_type, cover_image_path, created_at, updated_at, series, series_number, tags, asin, date_published, publisher, contributors FROM ebooks WHERE file_path = $1
+`
+
+func (q *Queries) GetEbookByFilePath(ctx context.Context, filePath string) (Ebooks, error) {
+	row := q.db.QueryRow(ctx, GetEbookByFilePath, filePath)
+	var i Ebooks
+	err := row.Scan(
+		&i.ID,
+		&i.Title,
+		&i.Author,
+		&i.Isbn,
+		&i.Description,
+		&i.FilePath,
+		&i.FileSize,
+		&i.MimeType,
+		&i.CoverImagePath,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+		&i.Series,
+		&i.SeriesNumber,
+		&i.Tags,
+		&i.Asin,
+		&i.DatePublished,
+		&i.Publisher,
+		&i.Contributors,
+	)
+	return i, err
+}
+
 const GetEbookRating = `-- name: GetEbookRating :one
 SELECT id, ebook_id, user_id, rating, created_at, updated_at FROM ebook_ratings WHERE ebook_id = $1 AND user_id = $2
 `
@@ -383,6 +448,35 @@ func (q *Queries) GetUserByUsername(ctx context.Context, username string) (Users
 	return i, err
 }
 
+const GetUserEbookFolders = `-- name: GetUserEbookFolders :many
+SELECT id, user_id, folder_path, created_at FROM user_ebook_folders WHERE user_id = $1 ORDER BY created_at
+`
+
+func (q *Queries) GetUserEbookFolders(ctx context.Context, userID pgtype.UUID) ([]UserEbookFolders, error) {
+	rows, err := q.db.Query(ctx, GetUserEbookFolders, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	items := []UserEbookFolders{}
+	for rows.Next() {
+		var i UserEbookFolders
+		if err := rows.Scan(
+			&i.ID,
+			&i.UserID,
+			&i.FolderPath,
+			&i.CreatedAt,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const ListEbooks = `-- name: ListEbooks :many
 SELECT id, title, author, isbn, description, file_path, file_size, mime_type, cover_image_path, created_at, updated_at, series, series_number, tags, asin, date_published, publisher, contributors FROM ebooks ORDER BY created_at DESC LIMIT $1 OFFSET $2
 `