Add historical flight track functionality

- Store track history with position, altitude, speed, and timestamp
- Automatic track point collection every 30 seconds when position changes
- API endpoint /api/aircraft/{hex}/history for individual aircraft tracks
- Frontend "Show History" button to display historical flight paths
- Click aircraft markers to show their historical track (dashed red line)
- Track cleanup: keep last 200 points per aircraft, 24-hour retention
- Add aircraft type badges in table view with color coding
- Start/end markers for historical tracks with timestamps

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

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

internal/client/dump1090.go

@@ -106,11 +106,28 @@ func (c *Dump1090Client) updateExistingAircraft(existing, update *parser.Aircraf
 	if update.Track != 0 {
 		existing.Track = update.Track
 	}
-	if update.Latitude != 0 {
+	if update.Latitude != 0 && update.Longitude != 0 {
 		existing.Latitude = update.Latitude
-	}
-	if update.Longitude != 0 {
 		existing.Longitude = update.Longitude
+		
+		// Add to track history if position changed significantly
+		if c.shouldAddTrackPoint(existing, update) {
+			trackPoint := parser.TrackPoint{
+				Timestamp: update.LastSeen,
+				Latitude:  update.Latitude,
+				Longitude: update.Longitude,
+				Altitude:  update.Altitude,
+				Speed:     update.GroundSpeed,
+				Track:     update.Track,
+			}
+			
+			existing.TrackHistory = append(existing.TrackHistory, trackPoint)
+			
+			// Keep only last 200 points (about 3-4 hours at 1 point/minute)
+			if len(existing.TrackHistory) > 200 {
+				existing.TrackHistory = existing.TrackHistory[1:]
+			}
+		}
 	}
 	if update.VertRate != 0 {
 		existing.VertRate = update.VertRate
@@ -121,6 +138,28 @@ func (c *Dump1090Client) updateExistingAircraft(existing, update *parser.Aircraf
 	existing.OnGround = update.OnGround
 }
 
+func (c *Dump1090Client) shouldAddTrackPoint(existing, update *parser.Aircraft) bool {
+	// Add track point if:
+	// 1. No history yet
+	if len(existing.TrackHistory) == 0 {
+		return true
+	}
+	
+	lastPoint := existing.TrackHistory[len(existing.TrackHistory)-1]
+	
+	// 2. At least 30 seconds since last point
+	if time.Since(lastPoint.Timestamp) < 30*time.Second {
+		return false
+	}
+	
+	// 3. Position changed by at least 0.001 degrees (~100m)
+	latDiff := existing.Latitude - lastPoint.Latitude
+	lonDiff := existing.Longitude - lastPoint.Longitude
+	distanceChange := latDiff*latDiff + lonDiff*lonDiff
+	
+	return distanceChange > 0.000001 // ~0.001 degrees squared
+}
+
 func (c *Dump1090Client) GetAircraftData() parser.AircraftData {
 	c.mutex.RLock()
 	defer c.mutex.RUnlock()
@@ -201,9 +240,20 @@ func (c *Dump1090Client) cleanupStaleAircraft() {
 	defer c.mutex.Unlock()
 
 	cutoff := time.Now().Add(-2 * time.Minute)
+	trackCutoff := time.Now().Add(-24 * time.Hour)
+	
 	for hex, aircraft := range c.aircraftMap {
 		if aircraft.LastSeen.Before(cutoff) {
 			delete(c.aircraftMap, hex)
+		} else {
+			// Clean up old track points (keep last 24 hours)
+			validTracks := make([]parser.TrackPoint, 0)
+			for _, point := range aircraft.TrackHistory {
+				if point.Timestamp.After(trackCutoff) {
+					validTracks = append(validTracks, point)
+				}
+			}
+			aircraft.TrackHistory = validTracks
 		}
 	}
 }