Fix map pin location selection issue

Problem: After dropping a pin on the map, clicking 'Use This Location'
showed 'No location selected' error message.

Root Cause: The onMapClick method was calling clearTempMarker() before
setting the new location, which reset selectedLocation and isLocationSelected
to null/false.

Solution: Reordered operations in onMapClick to only remove the old marker
without clearing the location state, then set the new location and create
the new marker.

This ensures the location state remains valid when the user clicks
'Use This Location' button.

static/map.js

@@ -254,12 +254,16 @@ class TreeTrackMap {
     onMapClick(e) {
         console.log('Map clicked at:', e.latlng);
         
+        // Remove existing temp marker first (before setting new location)
+        if (this.tempMarker) {
+            this.map.removeLayer(this.tempMarker);
+            this.tempMarker = null;
+        }
+        
+        // Now set the new location
         this.selectedLocation = e.latlng;
         this.isLocationSelected = true;
 
-        // Remove existing temp marker
-        this.clearTempMarker();
-
         // Create beautiful tree-shaped temp marker
         const tempIcon = L.divIcon({
             html: `
@@ -322,25 +326,33 @@ class TreeTrackMap {
     }
 
     useSelectedLocation() {
-        if (!this.selectedLocation) {
-            this.showMessage('No location selected', 'error');
+        if (!this.selectedLocation || !this.isLocationSelected) {
+            this.showMessage('No location selected. Please click on the map to drop a pin first.', 'error');
             return;
         }
 
-        // Store location for the form page
-        localStorage.setItem('selectedLocation', JSON.stringify({
-            lat: this.selectedLocation.lat,
-            lng: this.selectedLocation.lng
-        }));
+        try {
+            // Store location for the form page
+            const locationData = {
+                lat: this.selectedLocation.lat,
+                lng: this.selectedLocation.lng
+            };
+            
+            localStorage.setItem('selectedLocation', JSON.stringify(locationData));
 
-        // Clear the message and redirect
-        const messageElement = document.getElementById('message');
-        if(messageElement) messageElement.classList.remove('show');
-        this.showMessage('Location saved! Redirecting to form...', 'success');
-        
-        setTimeout(() => {
-            window.location.href = '/';
-        }, 1000);
+            // Clear any previous messages and show success
+            const messageElement = document.getElementById('message');
+            if(messageElement) messageElement.classList.remove('show');
+            this.showMessage('Location saved! Redirecting to form...', 'success');
+            
+            // Redirect after a short delay
+            setTimeout(() => {
+                window.location.href = '/';
+            }, 1500);
+        } catch (error) {
+            console.error('Error saving location:', error);
+            this.showMessage('Error saving location. Please try again.', 'error');
+        }
     }
 
     cancelLocationSelection() {