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/@babel/runtime/helpers/usingCtx.js

@@ -0,0 +1,59 @@
+function _usingCtx() {
+  var r = "function" == typeof SuppressedError ? SuppressedError : function (r, e) {
+      var n = Error();
+      return n.name = "SuppressedError", n.error = r, n.suppressed = e, n;
+    },
+    e = {},
+    n = [];
+  function using(r, e) {
+    if (null != e) {
+      if (Object(e) !== e) throw new TypeError("using declarations can only be used with objects, functions, null, or undefined.");
+      if (r) var o = e[Symbol.asyncDispose || Symbol["for"]("Symbol.asyncDispose")];
+      if (void 0 === o && (o = e[Symbol.dispose || Symbol["for"]("Symbol.dispose")], r)) var t = o;
+      if ("function" != typeof o) throw new TypeError("Object is not disposable.");
+      t && (o = function o() {
+        try {
+          t.call(e);
+        } catch (r) {
+          return Promise.reject(r);
+        }
+      }), n.push({
+        v: e,
+        d: o,
+        a: r
+      });
+    } else r && n.push({
+      d: e,
+      a: r
+    });
+    return e;
+  }
+  return {
+    e: e,
+    u: using.bind(null, !1),
+    a: using.bind(null, !0),
+    d: function d() {
+      var o,
+        t = this.e,
+        s = 0;
+      function next() {
+        for (; o = n.pop();) try {
+          if (!o.a && 1 === s) return s = 0, n.push(o), Promise.resolve().then(next);
+          if (o.d) {
+            var r = o.d.call(o.v);
+            if (o.a) return s |= 2, Promise.resolve(r).then(next, err);
+          } else s |= 1;
+        } catch (r) {
+          return err(r);
+        }
+        if (1 === s) return t !== e ? Promise.reject(t) : Promise.resolve();
+        if (t !== e) throw t;
+      }
+      function err(n) {
+        return t = t !== e ? new r(n, t) : n, next();
+      }
+      return next();
+    }
+  };
+}
+module.exports = _usingCtx, module.exports.__esModule = true, module.exports["default"] = module.exports;