Fix map centering to use calculated origin

Backend Changes:
- Added OriginConfig struct to server package
- Modified NewServer to accept origin configuration
- Added /api/origin endpoint to serve origin data to frontend
- Updated main.go to pass origin configuration to server

Frontend Changes:
- Modified initializeMap() to fetch origin from API before map creation
- Updated initializeCoverageMap() to also use origin data
- Added fallback coordinates in case API request fails
- Maps now center on the calculated origin position instead of hardcoded coordinates

The map now properly centers on the calculated average position of enabled
sources (or manually configured origin), providing a much better user experience
with appropriate regional view.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

internal/server/server.go

@@ -18,12 +18,20 @@ import (
 	"skyview/internal/merger"
 )
 
+// OriginConfig represents the reference point configuration
+type OriginConfig struct {
+	Latitude  float64 `json:"latitude"`
+	Longitude float64 `json:"longitude"`
+	Name      string  `json:"name,omitempty"`
+}
+
 // Server handles HTTP requests and WebSocket connections
 type Server struct {
 	port        int
 	merger      *merger.Merger
 	staticFiles embed.FS
 	server      *http.Server
+	origin      OriginConfig
 	
 	// WebSocket management
 	wsClients   map[*websocket.Conn]bool
@@ -50,11 +58,12 @@ type AircraftUpdate struct {
 }
 
 // NewServer creates a new HTTP server
-func NewServer(port int, merger *merger.Merger, staticFiles embed.FS) *Server {
+func NewServer(port int, merger *merger.Merger, staticFiles embed.FS, origin OriginConfig) *Server {
 	return &Server{
 		port:          port,
 		merger:        merger,
 		staticFiles:   staticFiles,
+		origin:        origin,
 		wsClients:     make(map[*websocket.Conn]bool),
 		upgrader: websocket.Upgrader{
 			CheckOrigin: func(r *http.Request) bool {
@@ -107,6 +116,7 @@ func (s *Server) setupRoutes() http.Handler {
 	api.HandleFunc("/aircraft/{icao}", s.handleGetAircraftDetails).Methods("GET")
 	api.HandleFunc("/sources", s.handleGetSources).Methods("GET")
 	api.HandleFunc("/stats", s.handleGetStats).Methods("GET")
+	api.HandleFunc("/origin", s.handleGetOrigin).Methods("GET")
 	api.HandleFunc("/coverage/{sourceId}", s.handleGetCoverage).Methods("GET")
 	api.HandleFunc("/heatmap/{sourceId}", s.handleGetHeatmap).Methods("GET")
 	
@@ -180,6 +190,11 @@ func (s *Server) handleGetStats(w http.ResponseWriter, r *http.Request) {
 	json.NewEncoder(w).Encode(stats)
 }
 
+func (s *Server) handleGetOrigin(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(s.origin)
+}
+
 func (s *Server) handleGetCoverage(w http.ResponseWriter, r *http.Request) {
 	vars := mux.Vars(r)
 	sourceID := vars["sourceId"]