feat: implement location selection interface with EXIF, GPS, and map picker

- Created LocationSelector component with three location input methods:
  * Auto-populate from photo EXIF data
  * Device GPS location capture with accuracy indicator
  * Interactive Leaflet map picker with draggable marker
- Added Ireland coordinate validation (lat: 51.4-55.4, lng: -10.5--5.5)
- Created coordinate utility functions for validation and formatting
- Added LocationSelectorDemo page for testing at /demo/location-selector
- Displays selected location with coordinates, source, and accuracy
- Provides clear error messages for validation failures
- Satisfies requirements 1.1, 1.2, 1.3, 8.2

src/utils/coordinates.ts

@@ -0,0 +1,70 @@
+/**
+ * Utility functions for coordinate validation and manipulation
+ */
+
+import type { Coordinates } from '@/types';
+
+// Ireland bounding box for coordinate validation
+export const IRELAND_BOUNDS = {
+  minLat: 51.4,
+  maxLat: 55.4,
+  minLng: -10.5,
+  maxLng: -5.5,
+};
+
+/**
+ * Validates if coordinates are within Ireland's boundaries
+ */
+export function isWithinIreland(lat: number, lng: number): boolean {
+  return (
+    lat >= IRELAND_BOUNDS.minLat &&
+    lat <= IRELAND_BOUNDS.maxLat &&
+    lng >= IRELAND_BOUNDS.minLng &&
+    lng <= IRELAND_BOUNDS.maxLng
+  );
+}
+
+/**
+ * Validates if coordinates object is within Ireland's boundaries
+ */
+export function validateIrelandCoordinates(coords: Coordinates): boolean {
+  return isWithinIreland(coords.latitude, coords.longitude);
+}
+
+/**
+ * Calculates the distance between two coordinates in meters using the Haversine formula
+ */
+export function calculateDistance(
+  coord1: Coordinates,
+  coord2: Coordinates
+): number {
+  const R = 6371e3; // Earth's radius in meters
+  const φ1 = (coord1.latitude * Math.PI) / 180;
+  const φ2 = (coord2.latitude * Math.PI) / 180;
+  const Δφ = ((coord2.latitude - coord1.latitude) * Math.PI) / 180;
+  const Δλ = ((coord2.longitude - coord1.longitude) * Math.PI) / 180;
+
+  const a =
+    Math.sin(Δφ / 2) * Math.sin(Δφ / 2) +
+    Math.cos(φ1) * Math.cos(φ2) * Math.sin(Δλ / 2) * Math.sin(Δλ / 2);
+  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+
+  return R * c;
+}
+
+/**
+ * Formats coordinates for display
+ */
+export function formatCoordinates(coords: Coordinates, precision: number = 6): string {
+  return `${coords.latitude.toFixed(precision)}, ${coords.longitude.toFixed(precision)}`;
+}
+
+/**
+ * Gets accuracy label based on accuracy value in meters
+ */
+export function getAccuracyLabel(accuracy: number): string {
+  if (accuracy < 10) return 'Excellent';
+  if (accuracy < 50) return 'Good';
+  if (accuracy < 100) return 'Fair';
+  return 'Poor';
+}

src/utils/index.ts

@@ -1,17 +1,7 @@
 // Utility functions for the Beach Litter Mapping Platform
 
-/**
- * Validates if coordinates are within Ireland's geographical bounds
- */
-export function isValidIrishCoordinates(lat: number, lng: number): boolean {
-  // Ireland approximate bounds
-  const MIN_LAT = 51.4;
-  const MAX_LAT = 55.4;
-  const MIN_LNG = -10.5;
-  const MAX_LNG = -5.5;
-
-  return lat >= MIN_LAT && lat <= MAX_LAT && lng >= MIN_LNG && lng <= MAX_LNG;
-}
+// Re-export coordinate utilities
+export * from './coordinates';
 
 /**
  * Formats a date to ISO 8601 format