Add a WebAssembly front end (ElementaryUI + JavaScriptKit)

[colemancda]

Summary

Adds a browser / WebAssembly front end (Web/) built with ElementaryUI and JavaScriptKit, reusing the existing FuelingModel Store, view-model logic, and CoreFueling entities unchanged — only the transport, persistence, and view layers are new. Mirrors the standalone-package approach already used for Android/, so the wasm-only dependency graph never touches the Darwin/Android/test builds.

Root package

• Require CoreModel 2.10.0 (brings InMemoryModelStorage + FetchRequest.evaluate).
• Add InMemoryStore — a @MainActor backend that is both ModelStorage and ViewContext over one dictionary — plus a Store(inMemory:) initializer. SQLite's SQLCipher C code can't compile for wasm32, so this is the browser's persistence layer (also handy for previews/tests).
• Gate CoreModelSQLite/SQLite and HTTPTypesFoundation/URLSession out of wasm (sqlitePlatforms/urlSessionPlatforms in the manifest, #if canImport(CoreModelSQLite) and !os(WASI) source guards). Android and Apple builds are unchanged.
• New InMemoryStoreTests covering read-back, fuel-price queries, and partial-update semantics.

Web target

• FetchHTTPClient — an HTTPClient transport over the browser fetch API (the wasm counterpart to URLSession / the Android JNI client).
• FuelingStore — an ElementaryUI @Reactive coordinator bridging the stdlib-@Observable Store into ElementaryUI's reactivity.
• ElementaryUI views: a searchable locations list and a location detail screen with live fuel prices.
• Vite toolchain (@elementary-swift/vite-plugin-swift-wasm, useEmbeddedSDK: false → full-Foundation WASI SDK), with the ElementaryUI browser runtime vendored (not published to npm).

Testing

• Full suite green on macOS (27 tests, including the SQLite backend).
• Verified end to end in a browser against Scripts/test-server.py: locations list, search, and per-location detail with correct addresses and fuel prices.

Run

python3 Scripts/test-server.py --port 8080
cd Web && npm install && npm run dev   # http://localhost:5173