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/leaflet/src/layer/vector/SVG.Util.js

@@ -0,0 +1,39 @@
+import Browser from '../../core/Browser';
+
+// @namespace SVG; @section
+// There are several static functions which can be called without instantiating L.SVG:
+
+// @function create(name: String): SVGElement
+// Returns a instance of [SVGElement](https://developer.mozilla.org/docs/Web/API/SVGElement),
+// corresponding to the class name passed. For example, using 'line' will return
+// an instance of [SVGLineElement](https://developer.mozilla.org/docs/Web/API/SVGLineElement).
+export function svgCreate(name) {
+	return document.createElementNS('http://www.w3.org/2000/svg', name);
+}
+
+// @function pointsToPath(rings: Point[], closed: Boolean): String
+// Generates a SVG path string for multiple rings, with each ring turning
+// into "M..L..L.." instructions
+export function pointsToPath(rings, closed) {
+	var str = '',
+	i, j, len, len2, points, p;
+
+	for (i = 0, len = rings.length; i < len; i++) {
+		points = rings[i];
+
+		for (j = 0, len2 = points.length; j < len2; j++) {
+			p = points[j];
+			str += (j ? 'L' : 'M') + p.x + ' ' + p.y;
+		}
+
+		// closes the ring for polygons; "x" is VML syntax
+		str += closed ? (Browser.svg ? 'z' : 'x') : '';
+	}
+
+	// SVG complains about empty path strings
+	return str || 'M0 0';
+}
+
+
+
+