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/lodash/clamp.js

@@ -0,0 +1,39 @@
+var baseClamp = require('./_baseClamp'),
+    toNumber = require('./toNumber');
+
+/**
+ * Clamps `number` within the inclusive `lower` and `upper` bounds.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Number
+ * @param {number} number The number to clamp.
+ * @param {number} [lower] The lower bound.
+ * @param {number} upper The upper bound.
+ * @returns {number} Returns the clamped number.
+ * @example
+ *
+ * _.clamp(-10, -5, 5);
+ * // => -5
+ *
+ * _.clamp(10, -5, 5);
+ * // => 5
+ */
+function clamp(number, lower, upper) {
+  if (upper === undefined) {
+    upper = lower;
+    lower = undefined;
+  }
+  if (upper !== undefined) {
+    upper = toNumber(upper);
+    upper = upper === upper ? upper : 0;
+  }
+  if (lower !== undefined) {
+    lower = toNumber(lower);
+    lower = lower === lower ? lower : 0;
+  }
+  return baseClamp(toNumber(number), lower, upper);
+}
+
+module.exports = clamp;