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/ajv/lib/runtime/quote.ts

@@ -0,0 +1,31 @@
+const rxEscapable =
+  // eslint-disable-next-line no-control-regex, no-misleading-character-class
+  /[\\"\u0000-\u001f\u007f-\u009f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g
+
+const escaped: {[K in string]?: string} = {
+  "\b": "\\b",
+  "\t": "\\t",
+  "\n": "\\n",
+  "\f": "\\f",
+  "\r": "\\r",
+  '"': '\\"',
+  "\\": "\\\\",
+}
+
+export default function quote(s: string): string {
+  rxEscapable.lastIndex = 0
+  return (
+    '"' +
+    (rxEscapable.test(s)
+      ? s.replace(rxEscapable, (a) => {
+          const c = escaped[a]
+          return typeof c === "string"
+            ? c
+            : "\\u" + ("0000" + a.charCodeAt(0).toString(16)).slice(-4)
+        })
+      : s) +
+    '"'
+  )
+}
+
+quote.code = 'require("ajv/dist/runtime/quote").default'