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/processor.js

@@ -0,0 +1,67 @@
+'use strict'
+
+let Document = require('./document')
+let LazyResult = require('./lazy-result')
+let NoWorkResult = require('./no-work-result')
+let Root = require('./root')
+
+class Processor {
+  constructor(plugins = []) {
+    this.version = '8.5.8'
+    this.plugins = this.normalize(plugins)
+  }
+
+  normalize(plugins) {
+    let normalized = []
+    for (let i of plugins) {
+      if (i.postcss === true) {
+        i = i()
+      } else if (i.postcss) {
+        i = i.postcss
+      }
+
+      if (typeof i === 'object' && Array.isArray(i.plugins)) {
+        normalized = normalized.concat(i.plugins)
+      } else if (typeof i === 'object' && i.postcssPlugin) {
+        normalized.push(i)
+      } else if (typeof i === 'function') {
+        normalized.push(i)
+      } else if (typeof i === 'object' && (i.parse || i.stringify)) {
+        if (process.env.NODE_ENV !== 'production') {
+          throw new Error(
+            'PostCSS syntaxes cannot be used as plugins. Instead, please use ' +
+              'one of the syntax/parser/stringifier options as outlined ' +
+              'in your PostCSS runner documentation.'
+          )
+        }
+      } else {
+        throw new Error(i + ' is not a PostCSS plugin')
+      }
+    }
+    return normalized
+  }
+
+  process(css, opts = {}) {
+    if (
+      !this.plugins.length &&
+      !opts.parser &&
+      !opts.stringifier &&
+      !opts.syntax
+    ) {
+      return new NoWorkResult(this, css, opts)
+    } else {
+      return new LazyResult(this, css, opts)
+    }
+  }
+
+  use(plugin) {
+    this.plugins = this.plugins.concat(this.normalize([plugin]))
+    return this
+  }
+}
+
+module.exports = Processor
+Processor.default = Processor
+
+Root.registerProcessor(Processor)
+Document.registerProcessor(Processor)