Run ruff check --fix: remove unused imports (F401), fix f-strings
without placeholders (F541), remove unused variables (F841), fix
duplicate dict key (F601).
Run isort --profile black: normalize import ordering across all files.
Run ruff format: apply consistent formatting (black-compatible) to
all 58 Python files.
3 intentional E402 remain (imports after require_yaml() must execute
after yaml is available).
resolve_platform_cores() links platforms to their cores via
three strategies: all_libretro, explicit list, system ID
fallback. Pack generation always includes core requirements
beyond platform baseline. Case-insensitive dedup prevents
conflicts on Windows/macOS. Data dir strip_components fixes
doubled paths for Dolphin and PPSSPP caches.
Identical _fetch_raw() implementation (URL fetch + cache + error handling)
was duplicated in 4 scrapers. Moved to BaseScraper.__init__ with url param.
Each scraper now passes url to super().__init__() and inherits _fetch_raw().
Eliminates ~48 lines of duplicated code.
DRY audit now clean: resolve logic in common.py, scraper CLI in base_scraper,
_fetch_raw in BaseScraper. Remaining duplications are justified (different
list_platforms semantics, context-specific hash computation).
