Look up country metadata via REST Countries. Pass alpha2 (2-letter ISO 3166-1), alpha3 (3-letter), or name (with optional fullText=true for exact match). Returns common + official name, ISO codes, region + subregion, independence + UN-member flags, capital(s), population, area km², landlocked flag, neighboring borders (alpha-3), timezones, currencies (code → name + symbol), languages, calling code, flag emoji + SVG/PNG URLs, lat/lng coordinates, Google Maps + OSM URLs, driving side, top-level domains.