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/parse.js

@@ -0,0 +1,42 @@
+'use strict'
+
+let Container = require('./container')
+let Input = require('./input')
+let Parser = require('./parser')
+
+function parse(css, opts) {
+  let input = new Input(css, opts)
+  let parser = new Parser(input)
+  try {
+    parser.parse()
+  } catch (e) {
+    if (process.env.NODE_ENV !== 'production') {
+      if (e.name === 'CssSyntaxError' && opts && opts.from) {
+        if (/\.scss$/i.test(opts.from)) {
+          e.message +=
+            '\nYou tried to parse SCSS with ' +
+            'the standard CSS parser; ' +
+            'try again with the postcss-scss parser'
+        } else if (/\.sass/i.test(opts.from)) {
+          e.message +=
+            '\nYou tried to parse Sass with ' +
+            'the standard CSS parser; ' +
+            'try again with the postcss-sass parser'
+        } else if (/\.less$/i.test(opts.from)) {
+          e.message +=
+            '\nYou tried to parse Less with ' +
+            'the standard CSS parser; ' +
+            'try again with the postcss-less parser'
+        }
+      }
+    }
+    throw e
+  }
+
+  return parser.root
+}
+
+module.exports = parse
+parse.default = parse
+
+Container.registerParse(parse)