Add a Nintendo DS port (Embedded Swift, CoreModel + Wi-Fi)

[colemancda]

Summary

Adds a Nintendo DS port (NDS/) built with Embedded Swift for the DS's ARM946E-S (armv5te-none-none-eabi), reusing the real model stack — CoreFueling entities and predicates on top of CoreModel's in-memory store and FetchRequest evaluation engine — with live data fetched over Wi‑Fi. No hardcoded locations, no hardcoded server.

Screen split: the top screen renders the UI through a software rasterizer; the bottom (touch) screen hosts libnds' on-screen keyboard, which types into the locations search field.

How it works

• Model layer, for real. The Makefile compiles FoundationEmbedded → CoreModel → CoreFueling as Embedded modules and links them into the ROM. Search runs through the actual Location.Query.search predicate and CoreModel's pure-Swift FetchRequest.evaluate; detail rows read FuelProduct entities through the location's relationship. The DS uses CoreModel.InMemoryStorage (the synchronous store) because bare-metal armv5te ships no _Concurrency runtime for the actor-based InMemoryModelStorage.
• Networking. dswifi associates via the firmware WFC settings, then plain BSD sockets issue HTTP GETs against /v1/locations and /v1/fuelprice. A small byte-scanning JSON walker parses the same {status, message, data} envelope the other front ends decode (Embedded Swift has no JSONDecoder) and maps records into CoreModel.ModelData, mirroring FuelingAPI's mapping key for key.
• Injected server. tools/gen_server.py bakes FUELING_SERVER_URL (the same variable the playground and Android use) into a generated, gitignored ServerConfig.swift, defaulting to the local test server. Hostnames resolve on-device via DNS. https is rejected at build time — the DS has no TLS stack.
• UI. Renderer, screen model and navigation are copied from ClassicUI's ports/NDS (branch feature/nds) and adapted: runtime byte-array titles instead of StaticString, a search bar, and right-aligned detail values.

Companion changes

• CoreFueling: Model.fueling now builds under Embedded (entity descriptions assembled from each type's own attribute/relationship tables, since the Embedded declarations don't conform to Entity); LocationCoordinate binds sin/cos/atan2 directly on bare-metal targets, which have no importable libc module.
• Scripts/test-server.py: new --bind option (default unchanged) so emulators reaching the host over NAT can be served.

Depends on PureSwift/CoreModel#29, which gates the async ModelStorage/actor on canImport(_Concurrency), publishes InMemoryStorage, and fixes an internal Collection.contains helper that was an every-element membership test rather than a subsequence search — invisible on platforms where Foundation's StringProtocol.contains shadows it, but under Embedded it made searching "mill" match "1150 Timber Lane".

Testing

• Root package: swift build + full suite, 27 tests pass.
• Verified end to end in melonDS against the local test server: Wi‑Fi associates, both endpoints fetch and parse, the list renders live data, typing "mill" on the touch keyboard filters to exactly the three correct matches, and the detail screen shows address/city/state/ZIP/phone/parking plus fuel prices.

Notes for reviewers

• Needs a Swift toolchain whose Embedded stdlib ships an armv5te-none-none-eabi slice (release toolchains only ship armv4t); override with make SWIFTC=…. Also devkitPro (devkitARM, libnds, calico, ndstool) and python3 with Pillow.
• melonDS's slirp does not implement the QEMU-style 10.0.2.2 host alias (connect fails with errno 113), so emulator testing points FUELING_SERVER_URL at the host's LAN IP with the test server bound to 0.0.0.0.
• The error screen surfaces the failed step, errno and HTTP status, with a Retry row.