Fix European trip return heuristic for weekend location tracking

Adjust European short trip heuristic from >3 days to >1 day to correctly
detect when user has returned home from European trips. This fixes the
April 29-30, 2023 case where the location incorrectly showed "Sankt Georg, Hamburg"
instead of "Bristol" when the user was free (no events scheduled) after
the foss-north trip ended on April 27.

The previous logic required more than 3 days to pass before assuming
return home from European countries, but for short European trips by
rail/ferry, users typically return within 1-2 days.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

node_modules/concat-map/test/map.js

@@ -0,0 +1,39 @@
+var concatMap = require('../');
+var test = require('tape');
+
+test('empty or not', function (t) {
+    var xs = [ 1, 2, 3, 4, 5, 6 ];
+    var ixes = [];
+    var ys = concatMap(xs, function (x, ix) {
+        ixes.push(ix);
+        return x % 2 ? [ x - 0.1, x, x + 0.1 ] : [];
+    });
+    t.same(ys, [ 0.9, 1, 1.1, 2.9, 3, 3.1, 4.9, 5, 5.1 ]);
+    t.same(ixes, [ 0, 1, 2, 3, 4, 5 ]);
+    t.end();
+});
+
+test('always something', function (t) {
+    var xs = [ 'a', 'b', 'c', 'd' ];
+    var ys = concatMap(xs, function (x) {
+        return x === 'b' ? [ 'B', 'B', 'B' ] : [ x ];
+    });
+    t.same(ys, [ 'a', 'B', 'B', 'B', 'c', 'd' ]);
+    t.end();
+});
+
+test('scalars', function (t) {
+    var xs = [ 'a', 'b', 'c', 'd' ];
+    var ys = concatMap(xs, function (x) {
+        return x === 'b' ? [ 'B', 'B', 'B' ] : x;
+    });
+    t.same(ys, [ 'a', 'B', 'B', 'B', 'c', 'd' ]);
+    t.end();
+});
+
+test('undefs', function (t) {
+    var xs = [ 'a', 'b', 'c', 'd' ];
+    var ys = concatMap(xs, function () {});
+    t.same(ys, [ undefined, undefined, undefined, undefined ]);
+    t.end();
+});