refactor: restructure project from bookmann to shelf

- Rename project from 'bookmann' to 'shelf'
- Move all backend/ contents to root level (flatten structure)
- Update Go module name from 'bookmann' to 'shelf'
- Update all import paths to use new 'shelf' module
- Update Dockerfile to work without backend/ subdirectory
- Update docker-compose.yml to use new structure and rename containers
- Update .gitignore for new file paths
- Update README.md with new project name and structure
- Regenerate database code with new module imports

internal/database/querier.go

@@ -0,0 +1,40 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.30.0
+
+package database
+
+import (
+	"context"
+
+	"github.com/jackc/pgx/v5/pgtype"
+)
+
+type Querier interface {
+	AddUserEbookFolder(ctx context.Context, arg AddUserEbookFolderParams) (UserEbookFolders, error)
+	CreateEbook(ctx context.Context, arg CreateEbookParams) (Ebooks, error)
+	CreateEbookRating(ctx context.Context, arg CreateEbookRatingParams) (EbookRatings, error)
+	CreateUser(ctx context.Context, arg CreateUserParams) (Users, error)
+	DeleteEbook(ctx context.Context, id pgtype.UUID) error
+	DeleteEbookRating(ctx context.Context, arg DeleteEbookRatingParams) error
+	DeleteReadingProgress(ctx context.Context, arg DeleteReadingProgressParams) error
+	DeleteUserEbookFolder(ctx context.Context, arg DeleteUserEbookFolderParams) error
+	GetEbook(ctx context.Context, id pgtype.UUID) (Ebooks, error)
+	GetEbookByFilePath(ctx context.Context, filePath string) (Ebooks, error)
+	GetEbookRating(ctx context.Context, arg GetEbookRatingParams) (EbookRatings, error)
+	GetEbookRatings(ctx context.Context, ebookID pgtype.UUID) ([]GetEbookRatingsRow, error)
+	GetReadingProgress(ctx context.Context, arg GetReadingProgressParams) (ReadingProgress, error)
+	GetUser(ctx context.Context, id pgtype.UUID) (GetUserRow, error)
+	GetUserByEmail(ctx context.Context, email string) (Users, error)
+	GetUserByEmailOrUsername(ctx context.Context, email string) (Users, error)
+	GetUserByUsername(ctx context.Context, username string) (Users, error)
+	GetUserEbookFolders(ctx context.Context, userID pgtype.UUID) ([]UserEbookFolders, error)
+	ListEbooks(ctx context.Context, arg ListEbooksParams) ([]Ebooks, error)
+	ListUsers(ctx context.Context) ([]ListUsersRow, error)
+	UpdateEbook(ctx context.Context, arg UpdateEbookParams) (Ebooks, error)
+	UpdateEbookRating(ctx context.Context, arg UpdateEbookRatingParams) (EbookRatings, error)
+	UpdateReadingProgress(ctx context.Context, arg UpdateReadingProgressParams) (ReadingProgress, error)
+	UpdateUserTheme(ctx context.Context, arg UpdateUserThemeParams) error
+}
+
+var _ Querier = (*Queries)(nil)