Replace get_ip_info + get_cached_ip_info pair with a single unshackle.core.utils.ip_info module providing a normalized return shape across providers. Adds optional ipinfo_api_key config for the ipinfo.io Lite endpoint (higher rate limits, ASN/org/continent data), swaps the ipapi.co fallback for ip-api.in, and migrates all callers (service, gluetun, remote_service, api/handlers, DSNP, YT) to the new import path. Auth token is sent per-request and never attached to the shared session headers.
- Create `unshackle/core/providers/` package with abstract base class, IMDBApi (free, no key), SIMKL, and TMDB provider implementations
- Add consensus-based ID enrichment: cross-references IMDB IDs with TMDB and SIMKL, drops all data from providers that disagree on tmdb_id (likely resolved to wrong title)
- Cache enriched IDs alongside raw provider data so they survive cache round-trips
- Genericize TitleCacher with `cache_provider()`/`get_cached_provider()` replacing provider-specific methods; respect `--no-cache` flag
- Add `--imdb` CLI flag to dl command for direct IMDB ID lookup
