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/jake/lib/task/directory_task.js

@@ -0,0 +1,30 @@
+let fs = require('fs');
+let FileTask = require('./file_task').FileTask;
+
+/**
+  @name jake
+  @namespace jake
+*/
+/**
+  @name jake.DirectoryTask
+  @constructor
+  @augments EventEmitter
+  @augments jake.Task
+  @augments jake.FileTask
+  @description A Jake DirectoryTask
+
+  @param {String} name The name of the directory to create.
+ */
+class DirectoryTask extends FileTask {
+  constructor(...args) {
+    super(...args);
+    if (fs.existsSync(this.name)) {
+      this.updateModTime();
+    }
+    else {
+      this.modTime = null;
+    }
+  }
+}
+
+exports.DirectoryTask = DirectoryTask;