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/parser/bin/babel-parser.js

@@ -0,0 +1,15 @@
+#!/usr/bin/env node
+/* eslint-disable no-var, unicorn/prefer-node-protocol */
+
+var parser = require("..");
+var fs = require("fs");
+
+var filename = process.argv[2];
+if (!filename) {
+  console.error("no filename specified");
+} else {
+  var file = fs.readFileSync(filename, "utf8");
+  var ast = parser.parse(file);
+
+  console.log(JSON.stringify(ast, null, "  "));
+}