…load and thread-safety fixes

- Add optional offline country/region lookup using alpslib-geo RgcHandler
- Automatically download and cache RGC database on first run from configured URL
- Fall back to online Photon/Komoot API if local database disabled or unavailable
- Mark rgcHandler field as volatile to guarantee cross-thread visibility
- Mark Module.enabled as volatile to ensure reliable isEnabled() checks across threads
- Schedule RgcHandler creation and all method calls on main thread to prevent concurrent access
- Create parent directories before FileOutputStream to handle first-run download
- Use try-with-resources for download streams to prevent resource leaks
- Schedule RGC lookups on main thread when called from worker threads in OpenStreetMapAPI
- Add getCCA2FromCountryName() fallback helper for country code lookup
- Add RGC configuration options: enabled, url, path under reverse-geocode.local-database
- Handle download failures gracefully with logging and fallback to API

Dependencies:
- Add com.alpsbte.alpslib:alpslib-geo:1.0.0

Files:
- build.gradle.kts: add alpslib-geo dependency
- gradle/libs.versions.toml: define alpslib-geo version
- settings.gradle.kts: enable mavenLocal() (TEMPORARY - disable before merge)
- NavigationModule.java: add RGC initialization with auto-download
- Module.java: mark enabled field volatile
- OpenStreetMapAPI.java: schedule RGC lookups on main thread
- NavUtils.java: add getCCA2FromCountryName() helper
- ConfigPaths.java: add RGC_LOCAL_DB_* constants
- WarpsComponent.java, WarpEditMenu.java: use fallback country code lookup
- config.yml: document RGC local-database settings