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/ajv/lib/vocabularies/validation/limitItems.ts

@@ -0,0 +1,26 @@
+import type {CodeKeywordDefinition, KeywordErrorDefinition} from "../../types"
+import type {KeywordCxt} from "../../compile/validate"
+import {_, str, operators} from "../../compile/codegen"
+
+const error: KeywordErrorDefinition = {
+  message({keyword, schemaCode}) {
+    const comp = keyword === "maxItems" ? "more" : "fewer"
+    return str`must NOT have ${comp} than ${schemaCode} items`
+  },
+  params: ({schemaCode}) => _`{limit: ${schemaCode}}`,
+}
+
+const def: CodeKeywordDefinition = {
+  keyword: ["maxItems", "minItems"],
+  type: "array",
+  schemaType: "number",
+  $data: true,
+  error,
+  code(cxt: KeywordCxt) {
+    const {keyword, data, schemaCode} = cxt
+    const op = keyword === "maxItems" ? operators.GT : operators.LT
+    cxt.fail$data(_`${data}.length ${op} ${schemaCode}`)
+  },
+}
+
+export default def