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/leaflet.offline/test/ControlSaveTilesTest.ts

@@ -0,0 +1,143 @@
+import { Map } from 'leaflet';
+import { assert } from 'chai';
+import { ControlSaveTiles, savetiles } from '../src/ControlSaveTiles';
+import { TileLayerOffline } from '../src/TileLayerOffline';
+import * as sinon from 'sinon';
+
+describe('control with defaults', () => {
+  let saveControl: ControlSaveTiles;
+  let baseLayer: TileLayerOffline;
+  beforeEach(() => {
+    const leafletMap = new Map(document.createElement('div'));
+    leafletMap.setView(
+      {
+        lat: 51.985,
+        lng: 5,
+      },
+      16,
+    );
+    baseLayer = new TileLayerOffline(
+      'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
+      {
+        subdomains: 'abc',
+      },
+    ).addTo(leafletMap);
+    saveControl = savetiles(baseLayer, {});
+    saveControl.addTo(leafletMap);
+    saveControl._rmTiles();
+  });
+  it('exists', () => {
+    assert.ok(savetiles);
+  });
+  it('adds button', () => {
+    const div = saveControl.onAdd();
+    assert.ok(div);
+    assert.lengthOf(div.querySelectorAll('a'), 2);
+  });
+  it('calculates storagesize', () =>
+    saveControl.setStorageSize().then((n) => {
+      assert.equal(n, 0);
+    }));
+  it('_saveTiles sets status', () => {
+    const stub = sinon
+      .stub(saveControl, '_loadTile')
+      .returns(Promise.resolve(new Blob()));
+    const resetstub = sinon.stub(saveControl, '_resetStatus');
+    saveControl._saveTiles();
+    assert.isObject(saveControl.status);
+    assert.isTrue(resetstub.calledOnce);
+    stub.resetBehavior();
+    resetstub.resetBehavior();
+  });
+  it('_saveTiles fires savestart with _tilesforSave prop', (done) => {
+    const stub = sinon
+      .stub(saveControl, '_loadTile')
+      .returns(Promise.resolve(new Blob()));
+    baseLayer.on('savestart', (status) => {
+      // TODO
+      // @ts-ignore
+      assert.lengthOf(status._tilesforSave, 1);
+      stub.resetBehavior();
+      done();
+    });
+    saveControl._saveTiles();
+  });
+
+  it('_saveTiles calls loadTile for each tile', () => {
+    const stub = sinon
+      .stub(saveControl, '_loadTile')
+      .returns(Promise.resolve(new Blob()));
+    saveControl._saveTiles();
+    assert.equal(
+      stub.callCount,
+      1,
+      `_loadTile has been called ${stub.callCount} times`,
+    );
+    stub.resetBehavior();
+  });
+});
+
+describe('control with different options', () => {
+  let leafletMap: Map;
+  let baseLayer: TileLayerOffline;
+  beforeEach(() => {
+    leafletMap = new Map(document.createElement('div'));
+    leafletMap.setView(
+      {
+        lat: 51.985,
+        lng: 5,
+      },
+      16,
+    );
+    baseLayer = new TileLayerOffline(
+      'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
+      {
+        subdomains: 'abc',
+      },
+    ).addTo(leafletMap);
+  });
+  it('_saveTiles calculates tiles for 2 zoomlevels', () => {
+    const c = savetiles(baseLayer, {
+      zoomlevels: [16, 17],
+    });
+    c.addTo(leafletMap);
+    c._rmTiles();
+    const stub = sinon
+      .stub(c, '_loadTile')
+      .returns(Promise.resolve(new Blob()));
+    c._saveTiles();
+    assert.isObject(c.status);
+    assert.isArray(c.status._tilesforSave);
+    assert.isAbove(stub.callCount, 1);
+    stub.resetBehavior();
+  });
+  it('_saveTiles calcs tiles for saveWhatYouSee', () => {
+    const c = savetiles(baseLayer, {
+      saveWhatYouSee: true,
+    });
+    c.addTo(leafletMap);
+    c._rmTiles();
+    const stub = sinon
+      .stub(c, '_loadTile')
+      .returns(Promise.resolve(new Blob()));
+    c._saveTiles();
+    assert.isObject(c.status);
+    assert.isArray(c.status._tilesforSave);
+    assert.equal(
+      stub.callCount,
+      4,
+      `_loadTile has been called ${stub.callCount} times`,
+    );
+    stub.resetBehavior();
+  });
+  it('calls confirm', () => {
+    const callback = sinon.spy();
+    const c = savetiles(baseLayer, {
+      confirm: callback,
+    });
+    c.addTo(leafletMap);
+    c._rmTiles();
+    c._saveTiles();
+    assert(callback.calledOnce);
+  });
+});