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/postcss/lib/root.js

@@ -0,0 +1,61 @@
+'use strict'
+
+let Container = require('./container')
+
+let LazyResult, Processor
+
+class Root extends Container {
+  constructor(defaults) {
+    super(defaults)
+    this.type = 'root'
+    if (!this.nodes) this.nodes = []
+  }
+
+  normalize(child, sample, type) {
+    let nodes = super.normalize(child)
+
+    if (sample) {
+      if (type === 'prepend') {
+        if (this.nodes.length > 1) {
+          sample.raws.before = this.nodes[1].raws.before
+        } else {
+          delete sample.raws.before
+        }
+      } else if (this.first !== sample) {
+        for (let node of nodes) {
+          node.raws.before = sample.raws.before
+        }
+      }
+    }
+
+    return nodes
+  }
+
+  removeChild(child, ignore) {
+    let index = this.index(child)
+
+    if (!ignore && index === 0 && this.nodes.length > 1) {
+      this.nodes[1].raws.before = this.nodes[index].raws.before
+    }
+
+    return super.removeChild(child)
+  }
+
+  toResult(opts = {}) {
+    let lazy = new LazyResult(new Processor(), this, opts)
+    return lazy.stringify()
+  }
+}
+
+Root.registerLazyResult = dependant => {
+  LazyResult = dependant
+}
+
+Root.registerProcessor = dependant => {
+  Processor = dependant
+}
+
+module.exports = Root
+Root.default = Root
+
+Container.registerRoot(Root)