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-build/build/lib/translate-url-to-sourcemap-paths.js

@@ -0,0 +1,33 @@
+"use strict";
+/*
+  Copyright 2021 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.
+*/
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.translateURLToSourcemapPaths = void 0;
+const fs_extra_1 = __importDefault(require("fs-extra"));
+const upath_1 = __importDefault(require("upath"));
+const errors_1 = require("./errors");
+function translateURLToSourcemapPaths(url, swSrc, swDest) {
+    let destPath = undefined;
+    let srcPath = undefined;
+    let warning = undefined;
+    if (url && !url.startsWith('data:')) {
+        const possibleSrcPath = upath_1.default.resolve(upath_1.default.dirname(swSrc), url);
+        if (fs_extra_1.default.existsSync(possibleSrcPath)) {
+            srcPath = possibleSrcPath;
+            destPath = upath_1.default.resolve(upath_1.default.dirname(swDest), url);
+        }
+        else {
+            warning = `${errors_1.errors['cant-find-sourcemap']} ${possibleSrcPath}`;
+        }
+    }
+    return { destPath, srcPath, warning };
+}
+exports.translateURLToSourcemapPaths = translateURLToSourcemapPaths;