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/package-json-from-dist/README.md

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+# package-json-from-dist
+
+Sometimes you want to load the `package.json` into your
+TypeScript program, and it's tempting to just `import
+'../package.json'`, since that seems to work.
+
+However, this requires `tsc` to make an entire copy of your
+`package.json` file into the `dist` folder, which is a problem if
+you're using something like
+[tshy](https://github.com/isaacs/tshy), which uses the
+`package.json` file in dist for another purpose. Even when that
+does work, it's asking the module system to do a bunch of extra
+fs system calls, just to load a version number or something. (See
+[this issue](https://github.com/isaacs/tshy/issues/61).)
+
+This module helps by just finding the package.json file
+appropriately, and reading and parsing it in the most normal
+fashion.
+
+## Caveats
+
+This _only_ works if your code builds into a target folder called
+`dist`, which is in the root of the package. It also requires
+that you do not have a folder named `node_modules` anywhere
+within your dev environment, or else it'll get the wrong answers
+there. (But, at least, that'll be in dev, so you're pretty likely
+to notice.)
+
+If you build to some other location, then you'll need a different
+approach. (Feel free to fork this module and make it your own, or
+just put the code right inline, there's not much of it.)
+
+## USAGE
+
+```js
+// src/index.ts
+import {
+  findPackageJson,
+  loadPackageJson,
+} from 'package-json-from-dist'
+
+const pj = findPackageJson(import.meta.url)
+console.log(`package.json found at ${pj}`)
+
+const pkg = loadPackageJson(import.meta.url)
+console.log(`Hello from ${pkg.name}@${pkg.version}`)
+```
+
+If your module is not directly in the `./src` folder, then you need
+to specify the path that you would expect to find the
+`package.json` when it's _not_ built to the `dist` folder.
+
+```js
+// src/components/something.ts
+import {
+  findPackageJson,
+  loadPackageJson,
+} from 'package-json-from-dist'
+
+const pj = findPackageJson(import.meta.url, '../../package.json')
+console.log(`package.json found at ${pj}`)
+
+const pkg = loadPackageJson(import.meta.url, '../../package.json')
+console.log(`Hello from ${pkg.name}@${pkg.version}`)
+```
+
+When running from CommmonJS, use `__filename` instead of
+`import.meta.url`.
+
+```js
+// src/index.cts
+import {
+  findPackageJson,
+  loadPackageJson,
+} from 'package-json-from-dist'
+
+const pj = findPackageJson(__filename)
+console.log(`package.json found at ${pj}`)
+
+const pkg = loadPackageJson(__filename)
+console.log(`Hello from ${pkg.name}@${pkg.version}`)
+```
+
+Since [tshy](https://github.com/isaacs/tshy) builds _both_
+CommonJS and ESM by default, you may find that you need a
+CommonJS override and some `//@ts-ignore` magic to make it work.
+
+`src/pkg.ts`:
+
+```js
+import {
+  findPackageJson,
+  loadPackageJson,
+} from 'package-json-from-dist'
+//@ts-ignore
+export const pkg = loadPackageJson(import.meta.url)
+//@ts-ignore
+export const pj = findPackageJson(import.meta.url)
+```
+
+`src/pkg-cjs.cts`:
+
+```js
+import {
+  findPackageJson,
+  loadPackageJson,
+} from 'package-json-from-dist'
+export const pkg = loadPackageJson(__filename)
+export const pj = findPackageJson(__filename)
+```