Phase 1: foundation modules

Central Config with all tunables (retention, GPS timeout, colors,
event type keys, menu item metadata). Event / EventStore handle
persistence via Application.Storage with 7-day pruning. Logger
mirrors the same retention. LayoutMetrics and Haversine provide
resolution-independent geometry helpers. German UI strings and
placeholder menu icons landed alongside so the build stays green.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

source/Haversine.mc

@@ -0,0 +1,25 @@
+import Toybox.Lang;
+import Toybox.Math;
+
+// Great-circle distance between two WGS84 coordinates, in meters.
+module Haversine {
+
+    const EARTH_RADIUS_M = 6371000.0;
+
+    function distance(lat1 as Float, lon1 as Float, lat2 as Float, lon2 as Float) as Float {
+        var dLat = _toRad(lat2 - lat1);
+        var dLon = _toRad(lon2 - lon1);
+        var rLat1 = _toRad(lat1);
+        var rLat2 = _toRad(lat2);
+
+        var a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
+              + Math.cos(rLat1) * Math.cos(rLat2)
+              * Math.sin(dLon / 2) * Math.sin(dLon / 2);
+        var c = 2 * Math.asin(Math.sqrt(a));
+        return (EARTH_RADIUS_M * c).toFloat();
+    }
+
+    function _toRad(deg as Float) as Float {
+        return (deg * Math.PI / 180.0).toFloat();
+    }
+}