Add location-aware automatic default bounding box

The OpenSky "Default bounding box" now follows where flying happens.
A new "Automatic" picker mode (the default) resolves the live-map area
from a location cascade — drone telemetry → phone GPS → browser
geolocation → the user's Region country → Europe — instead of a fixed
box. Manual presets and Custom coordinates still work.

- Web App: new shared countries.js dataset (all countries + bbox,
  offline point→country); the bbox picker gains all European countries
  and an Automatic option (client pref prefs.autoBbox); the Region
  setting expands from 6 locale entries to all countries; the live map
  resolves the cascade each poll and sends it as ?bbox=.
- API Server: the states endpoint accepts and validates a ?bbox=
  override (validBBox); the Web App BFF forwards the query; the hub
  relays new phoneLatitude/phoneLongitude telemetry to the Web App.
- Fly App: reports the phone's own GPS (geolocator) alongside
  telemetry, used as the "your location" fallback.
- API panel: the OpenSky bbox picker lists all European countries.

Builds verified across web, panel, both Go modules and the Fly App
APK. Region list, Automatic default and the cascade ?bbox= override
verified in the browser.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

API Server/internal/hub/models.go

@@ -11,6 +11,10 @@ type Telemetry struct {
 	Altitude       *float64 `json:"altitude,omitempty"`
 	Latitude       *float64 `json:"latitude,omitempty"`
 	Longitude      *float64 `json:"longitude,omitempty"`
+	// Phone's own GPS (reported by the Fly App), distinct from the drone's fix
+	// above — used as a location fallback for the Web App's auto bounding box.
+	PhoneLatitude  *float64 `json:"phoneLatitude,omitempty"`
+	PhoneLongitude *float64 `json:"phoneLongitude,omitempty"`
 	VelocityX      *float64 `json:"velocityX,omitempty"`
 	VelocityY      *float64 `json:"velocityY,omitempty"`
 	VelocityZ      *float64 `json:"velocityZ,omitempty"`
@@ -100,6 +104,12 @@ func applyTelemetry(t *Telemetry, raw map[string]any) {
 	if v, ok := toFloat(raw["longitude"]); ok {
 		t.Longitude = &v
 	}
+	if v, ok := toFloat(raw["phoneLatitude"]); ok {
+		t.PhoneLatitude = &v
+	}
+	if v, ok := toFloat(raw["phoneLongitude"]); ok {
+		t.PhoneLongitude = &v
+	}
 	if v, ok := toFloat(raw["velocityX"]); ok {
 		t.VelocityX = &v
 	}