feat(errors): add error handling for no rows in PostgreSQL queries

docs(postgres): update README and schema files for migrations and foreign key handling

docs(guidelines): update iteration and JSON field semantics rules

feat(logger): add NoopLogger implementation for Logger interface

feat(errors): add foreign key violation handling in PostgreSQL error management

docs(service): remove outdated README for internal/service

refactor(auth): reorganize external repository structure for OAuth and OTP

docs(repository): update README with repository interface guidelines

docs(json): introduce JSON field semantics guidelines for API responses

docs(sql): refine database interaction guidelines to enhance performance and clarity

docs(sql): add guidelines to prevent N+1 queries and optimize database interactions

docs(sql): add type alignment guidelines for database interactions

feat(errors): enhance error handling for PostgreSQL write operations

refactor(database): update schema and models to use BIGINT for IDs and VARCHAR for string fields

feat(errors): implement sentinel error handling for database operations