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/workbox-core/copyResponse.js

@@ -0,0 +1,57 @@
+/*
+  Copyright 2019 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+import { canConstructResponseFromBodyStream } from './_private/canConstructResponseFromBodyStream.js';
+import { WorkboxError } from './_private/WorkboxError.js';
+import './_version.js';
+/**
+ * Allows developers to copy a response and modify its `headers`, `status`,
+ * or `statusText` values (the values settable via a
+ * [`ResponseInit`]{@link https://developer.mozilla.org/en-US/docs/Web/API/Response/Response#Syntax}
+ * object in the constructor).
+ * To modify these values, pass a function as the second argument. That
+ * function will be invoked with a single object with the response properties
+ * `{headers, status, statusText}`. The return value of this function will
+ * be used as the `ResponseInit` for the new `Response`. To change the values
+ * either modify the passed parameter(s) and return it, or return a totally
+ * new object.
+ *
+ * This method is intentionally limited to same-origin responses, regardless of
+ * whether CORS was used or not.
+ *
+ * @param {Response} response
+ * @param {Function} modifier
+ * @memberof workbox-core
+ */
+async function copyResponse(response, modifier) {
+    let origin = null;
+    // If response.url isn't set, assume it's cross-origin and keep origin null.
+    if (response.url) {
+        const responseURL = new URL(response.url);
+        origin = responseURL.origin;
+    }
+    if (origin !== self.location.origin) {
+        throw new WorkboxError('cross-origin-copy-response', { origin });
+    }
+    const clonedResponse = response.clone();
+    // Create a fresh `ResponseInit` object by cloning the headers.
+    const responseInit = {
+        headers: new Headers(clonedResponse.headers),
+        status: clonedResponse.status,
+        statusText: clonedResponse.statusText,
+    };
+    // Apply any user modifications.
+    const modifiedResponseInit = modifier ? modifier(responseInit) : responseInit;
+    // Create the new response from the body stream and `ResponseInit`
+    // modifications. Note: not all browsers support the Response.body stream,
+    // so fall back to reading the entire body into memory as a blob.
+    const body = canConstructResponseFromBodyStream()
+        ? clonedResponse.body
+        : await clonedResponse.blob();
+    return new Response(body, modifiedResponseInit);
+}
+export { copyResponse };