fix: location fallback to constants, compact card sizing

- Add third location fallback to utils/constants (London 51.5074/-0.1278)
  so location always resolves even without GPS or env vars configured
- Remove min-height from sys-card to eliminate wasted space
- Switch System Info to vertical key-value layout filling the card
- Clean up OS string (strip glibc suffix), use locale date for boot time
- Bump info grid font size from 11px to 12px for readability

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

routes/system.py

@@ -452,7 +452,7 @@ def _get_observer_location() -> dict[str, Any]:
             if pos.altitude is not None:
                 gps_meta['altitude'] = round(pos.altitude, 1)
 
-    # Fall back to config defaults
+    # Fall back to config env vars
     if lat is None:
         with contextlib.suppress(Exception):
             from config import DEFAULT_LATITUDE, DEFAULT_LONGITUDE
@@ -460,6 +460,14 @@ def _get_observer_location() -> dict[str, Any]:
             if DEFAULT_LATITUDE != 0.0 or DEFAULT_LONGITUDE != 0.0:
                 lat, lon, source = DEFAULT_LATITUDE, DEFAULT_LONGITUDE, 'config'
 
+    # Fall back to hardcoded constants (London)
+    if lat is None:
+        with contextlib.suppress(Exception):
+            from utils.constants import DEFAULT_LATITUDE as CONST_LAT
+            from utils.constants import DEFAULT_LONGITUDE as CONST_LON
+
+            lat, lon, source = CONST_LAT, CONST_LON, 'default'
+
     result: dict[str, Any] = {'lat': lat, 'lon': lon, 'source': source}
     if gps_meta:
         result['gps'] = gps_meta

static/css/modes/system.css

@@ -32,7 +32,6 @@
     border: 1px solid var(--border-color, #2a2a4a);
     border-radius: 6px;
     padding: 16px;
-    min-height: 120px;
 }
 
 .sys-card-wide {
@@ -464,17 +463,24 @@
     background: var(--bg-primary, #0d0d1a);
 }
 
-/* System info — horizontal layout */
+/* System info — vertical layout to fill card */
 .sys-info-grid {
     display: flex;
-    flex-wrap: wrap;
-    gap: 4px 20px;
-    font-size: 11px;
+    flex-direction: column;
+    gap: 6px;
+    font-size: 12px;
     color: var(--text-dim, #8888aa);
 }
 
 .sys-info-item {
-    white-space: nowrap;
+    display: flex;
+    justify-content: space-between;
+    padding: 2px 0;
+    border-bottom: 1px solid rgba(255, 255, 255, 0.04);
+}
+
+.sys-info-item:last-child {
+    border-bottom: none;
 }
 
 .sys-info-item strong {

static/js/modes/system.js

@@ -612,19 +612,19 @@ const SystemHealth = (function () {
         var sys = m.system || {};
         var html = '<div class="sys-card-header">System Info</div><div class="sys-card-body"><div class="sys-info-grid">';
 
-        html += '<div class="sys-info-item"><strong>Host:</strong> ' + escHtml(sys.hostname || '--') + '</div>';
-        html += '<div class="sys-info-item"><strong>OS:</strong> ' + escHtml(sys.platform || '--') + '</div>';
-        html += '<div class="sys-info-item"><strong>Python:</strong> ' + escHtml(sys.python || '--') + '</div>';
-        html += '<div class="sys-info-item"><strong>App:</strong> v' + escHtml(sys.version || '--') + '</div>';
-        html += '<div class="sys-info-item"><strong>Uptime:</strong> ' + escHtml(sys.uptime_human || '--') + '</div>';
+        html += '<div class="sys-info-item"><strong>Host</strong><span>' + escHtml(sys.hostname || '--') + '</span></div>';
+        html += '<div class="sys-info-item"><strong>OS</strong><span>' + escHtml((sys.platform || '--').replace(/-with-glibc[\d.]+/, '')) + '</span></div>';
+        html += '<div class="sys-info-item"><strong>Python</strong><span>' + escHtml(sys.python || '--') + '</span></div>';
+        html += '<div class="sys-info-item"><strong>App</strong><span>v' + escHtml(sys.version || '--') + '</span></div>';
+        html += '<div class="sys-info-item"><strong>Uptime</strong><span>' + escHtml(sys.uptime_human || '--') + '</span></div>';
 
         if (m.boot_time) {
             var bootDate = new Date(m.boot_time * 1000);
-            html += '<div class="sys-info-item"><strong>Boot:</strong> ' + escHtml(bootDate.toUTCString()) + '</div>';
+            html += '<div class="sys-info-item"><strong>Boot</strong><span>' + escHtml(bootDate.toLocaleString()) + '</span></div>';
         }
 
         if (m.network && m.network.connections != null) {
-            html += '<div class="sys-info-item"><strong>Connections:</strong> ' + m.network.connections + '</div>';
+            html += '<div class="sys-info-item"><strong>Connections</strong><span>' + m.network.connections + '</span></div>';
         }
 
         html += '</div></div>';

tests/test_system.py

@@ -169,14 +169,17 @@ def test_location_from_gps(client):
     assert data['gps']['altitude'] == 45.0
 
 
-def test_location_falls_back_to_config(client):
-    """Location endpoint returns config defaults when GPS unavailable."""
+def test_location_falls_back_to_defaults(client):
+    """Location endpoint returns constants defaults when GPS and config unavailable."""
     _login(client)
-    with patch('utils.gps.get_current_position', return_value=None):
-        resp = client.get('/system/location')
+    resp = client.get('/system/location')
     assert resp.status_code == 200
     data = resp.get_json()
     assert 'source' in data
+    # Should get location from config or default constants
+    assert data['lat'] is not None
+    assert data['lon'] is not None
+    assert data['source'] in ('config', 'default')
 
 
 def test_weather_requires_location(client):