Add progressive web app companion for cross-platform access

Vite + TypeScript PWA that mirrors the Android app's core features:
- Pre-processed shelter data (build-time UTM33N→WGS84 conversion)
- Leaflet map with shelter markers, user location, and offline tiles
- Canvas compass arrow (ported from DirectionArrowView.kt)
- IndexedDB shelter cache with 7-day staleness check
- Service worker with CacheFirst tiles and precached app shell
- i18n for en, nb, nn (ported from Android strings.xml)
- iOS/Android compass handling with low-pass filter
- Respects user map interaction (no auto-snap on pan/zoom)
- Build revision cache-breaker for reliable SW updates

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

pwa/node_modules/function-bind/implementation.js

@@ -0,0 +1,84 @@
+'use strict';
+
+/* eslint no-invalid-this: 1 */
+
+var ERROR_MESSAGE = 'Function.prototype.bind called on incompatible ';
+var toStr = Object.prototype.toString;
+var max = Math.max;
+var funcType = '[object Function]';
+
+var concatty = function concatty(a, b) {
+    var arr = [];
+
+    for (var i = 0; i < a.length; i += 1) {
+        arr[i] = a[i];
+    }
+    for (var j = 0; j < b.length; j += 1) {
+        arr[j + a.length] = b[j];
+    }
+
+    return arr;
+};
+
+var slicy = function slicy(arrLike, offset) {
+    var arr = [];
+    for (var i = offset || 0, j = 0; i < arrLike.length; i += 1, j += 1) {
+        arr[j] = arrLike[i];
+    }
+    return arr;
+};
+
+var joiny = function (arr, joiner) {
+    var str = '';
+    for (var i = 0; i < arr.length; i += 1) {
+        str += arr[i];
+        if (i + 1 < arr.length) {
+            str += joiner;
+        }
+    }
+    return str;
+};
+
+module.exports = function bind(that) {
+    var target = this;
+    if (typeof target !== 'function' || toStr.apply(target) !== funcType) {
+        throw new TypeError(ERROR_MESSAGE + target);
+    }
+    var args = slicy(arguments, 1);
+
+    var bound;
+    var binder = function () {
+        if (this instanceof bound) {
+            var result = target.apply(
+                this,
+                concatty(args, arguments)
+            );
+            if (Object(result) === result) {
+                return result;
+            }
+            return this;
+        }
+        return target.apply(
+            that,
+            concatty(args, arguments)
+        );
+
+    };
+
+    var boundLength = max(0, target.length - args.length);
+    var boundArgs = [];
+    for (var i = 0; i < boundLength; i++) {
+        boundArgs[i] = '$' + i;
+    }
+
+    bound = Function('binder', 'return function (' + joiny(boundArgs, ',') + '){ return binder.apply(this,arguments); }')(binder);
+
+    if (target.prototype) {
+        var Empty = function Empty() {};
+        Empty.prototype = target.prototype;
+        bound.prototype = new Empty();
+        Empty.prototype = null;
+    }
+
+    return bound;
+};