Declared events: announced GPS tests

Announced US GPS interference tests, parsed from the FAA's public flight advisories (SPANS notices at faasafety.gov; US government work, public domain). One record per test: id, place, centre, daily windows in UTC, radius by altitude (NM), links to the notice and advisory. Refreshed every morning by .github/workflows/daily.yml (pipeline/faa_gps_tests.py --rss); history from Sep 2025. Used by the map to tag anomalies and bursts that fall inside an announced test.