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/applicator/propertyNames.ts

@@ -0,0 +1,50 @@
+import type {
+  CodeKeywordDefinition,
+  ErrorObject,
+  KeywordErrorDefinition,
+  AnySchema,
+} from "../../types"
+import type {KeywordCxt} from "../../compile/validate"
+import {_, not} from "../../compile/codegen"
+import {alwaysValidSchema} from "../../compile/util"
+
+export type PropertyNamesError = ErrorObject<"propertyNames", {propertyName: string}, AnySchema>
+
+const error: KeywordErrorDefinition = {
+  message: "property name must be valid",
+  params: ({params}) => _`{propertyName: ${params.propertyName}}`,
+}
+
+const def: CodeKeywordDefinition = {
+  keyword: "propertyNames",
+  type: "object",
+  schemaType: ["object", "boolean"],
+  error,
+  code(cxt: KeywordCxt) {
+    const {gen, schema, data, it} = cxt
+    if (alwaysValidSchema(it, schema)) return
+    const valid = gen.name("valid")
+
+    gen.forIn("key", data, (key) => {
+      cxt.setParams({propertyName: key})
+      cxt.subschema(
+        {
+          keyword: "propertyNames",
+          data: key,
+          dataTypes: ["string"],
+          propertyName: key,
+          compositeRule: true,
+        },
+        valid
+      )
+      gen.if(not(valid), () => {
+        cxt.error(true)
+        if (!it.allErrors) gen.break()
+      })
+    })
+
+    cxt.ok(valid)
+  },
+}
+
+export default def