feat: Add comprehensive backend validation, toast notifications, and Tokyo Night theme

- Backend: Add server-side validation with go-playground/validator/v10
- Frontend: Add toast notifications for API errors with @zerodevx/svelte-toast
- UI: Complete Tokyo Night theme redesign with modern animations
- Docs: Update COMPLETE_DOCUMENTATION.md and README.md with all enhancements
- Validation: Email format, password strength, and input sanitization
- UX: Real-time error feedback, loading states, and responsive design

backend/internal/database/querier.go

@@ -0,0 +1,29 @@
+// 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 {
+	CreateEbook(ctx context.Context, arg CreateEbookParams) (Ebooks, error)
+	CreateUser(ctx context.Context, arg CreateUserParams) (Users, error)
+	DeleteEbook(ctx context.Context, id pgtype.UUID) error
+	DeleteReadingProgress(ctx context.Context, arg DeleteReadingProgressParams) error
+	GetEbook(ctx context.Context, id pgtype.UUID) (Ebooks, 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)
+	ListEbooks(ctx context.Context, arg ListEbooksParams) ([]Ebooks, error)
+	UpdateEbook(ctx context.Context, arg UpdateEbookParams) (Ebooks, error)
+	UpdateReadingProgress(ctx context.Context, arg UpdateReadingProgressParams) (ReadingProgress, error)
+}
+
+var _ Querier = (*Queries)(nil)