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/js-tokens/index.js

@@ -0,0 +1,23 @@
+// Copyright 2014, 2015, 2016, 2017, 2018 Simon Lydell
+// License: MIT. (See LICENSE.)
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+})
+
+// This regex comes from regex.coffee, and is inserted here by generate-index.js
+// (run `npm run build`).
+exports.default = /((['"])(?:(?!\2|\\).|\\(?:\r\n|[\s\S]))*(\2)?|`(?:[^`\\$]|\\[\s\S]|\$(?!\{)|\$\{(?:[^{}]|\{[^}]*\}?)*\}?)*(`)?)|(\/\/.*)|(\/\*(?:[^*]|\*(?!\/))*(\*\/)?)|(\/(?!\*)(?:\[(?:(?![\]\\]).|\\.)*\]|(?![\/\]\\]).|\\.)+\/(?:(?!\s*(?:\b|[\u0080-\uFFFF$\\'"~({]|[+\-!](?!=)|\.?\d))|[gmiyus]{1,6}\b(?![\u0080-\uFFFF$\\]|\s*(?:[+\-*%&|^<>!=?({]|\/(?![\/*])))))|(0[xX][\da-fA-F]+|0[oO][0-7]+|0[bB][01]+|(?:\d*\.\d+|\d+\.?)(?:[eE][+-]?\d+)?)|((?!\d)(?:(?!\s)[$\w\u0080-\uFFFF]|\\u[\da-fA-F]{4}|\\u\{[\da-fA-F]+\})+)|(--|\+\+|&&|\|\||=>|\.{3}|(?:[+\-\/%&|^]|\*{1,2}|<{1,2}|>{1,3}|!=?|={1,2})=?|[?~.,:;[\](){}])|(\s+)|(^$|[\s\S])/g
+
+exports.matchToToken = function(match) {
+  var token = {type: "invalid", value: match[0], closed: undefined}
+       if (match[ 1]) token.type = "string" , token.closed = !!(match[3] || match[4])
+  else if (match[ 5]) token.type = "comment"
+  else if (match[ 6]) token.type = "comment", token.closed = !!match[7]
+  else if (match[ 8]) token.type = "regex"
+  else if (match[ 9]) token.type = "number"
+  else if (match[10]) token.type = "name"
+  else if (match[11]) token.type = "punctuator"
+  else if (match[12]) token.type = "whitespace"
+  return token
+}