Fix coordinate parsing to handle DMS format and prevent stack traces

- Add parse_coordinate() function to handle both decimal degrees and DMS format
- Replace direct float() conversion with robust coordinate parsing
- Add proper validation for latitude/longitude ranges
- Create user-friendly error page instead of showing stack traces
- Support formats like "56°5'58.56"N" and "3°22'33.71"W"
- Update both /detail and / routes with improved error handling

Fixes #29: Don't return stack trace when lat/lon are not integers

templates/coordinate_error.html

@@ -0,0 +1,40 @@
+{% extends "base.html" %}
+
+{% block title %}Geocode to Commons: coordinate error{% endblock %}
+
+
+{% block content %}
+<div class="m-3">
+<h1>Geocode coordinates to Commons Category</h1>
+
+<div class="alert alert-danger" role="alert">
+  {{ error }}
+</div>
+
+
+<div class="coordinates">
+    <strong>Received coordinates:</strong><br>
+    Latitude: {{ lat_str }}<br>
+    Longitude: {{ lon_str }}
+</div>
+
+<div class="help-section">
+    <h2 class="help-title">Supported coordinate formats:</h2>
+
+    <div class="examples">
+        <div class="example">Decimal degrees: 56.099600, -3.376031</div>
+        <div class="example">DMS format: 56°5'58.56"N, 3°22'33.71"W</div>
+        <div class="example">Mixed format: 56.099600, 3°22'33.71"W</div>
+    </div>
+
+
+    <p>
+      <div>Latitude must be between -90 and 90 degrees.</div>
+      <div>Longitude must be between -180 and 180 degrees.</div>
+    </p>
+</div>
+
+<a href="{{ url_for('index') }}" class="back-link">← Back to Home</a>
+
+</div>
+{% endblock %}