Add Switch OTA launcher with unified SD zip and quiet UI.

Ships a dual-NRO native launcher that checks GitHub Releases, updates both NROs from gen1recomp-*-switch.zip with matching NACP versions, and stays silent unless an update needs confirm.

native/switch-ota-launcher/README.md

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+# Native Switch OTA launcher
+
+In-console updates for Gen1Recomp on Nintendo Switch. This NRO is the **hbmenu
+entry** (`gen1recomp.nro`). It checks GitHub Releases quietly (no console flash
+when you are already up to date or offline). Only if a newer release exists
+does it prompt to download the same `gen1recomp-*-switch.zip` used for install,
+verify SHA-256 from `sha256sums.txt`, replace **both** `gen1recomp-game.nro`
+and `gen1recomp.nro` (matching NACP version for hbmenu/Sphaira), then hand off
+with `envSetNextLoad`.
+
+The LÖVE self-updater (`src/update/Check.lua`) stays **disabled** on NX.
+Protocol contract (also in Lua): `src/update/SwitchOta.lua`.
+NACP icon: `assets/switch/icon.jpg`.
+
+## Layout on microSD
+
+```text
+sdmc:/switch/gen1recomp/gen1recomp.nro        ← this launcher
+sdmc:/switch/gen1recomp/gen1recomp-game.nro   ← fused LÖVE game
+sdmc:/switch/gen1recomp/version.txt          ← installed X.Y.Z
+sdmc:/switch/gen1recomp/pokemon-love2d/      ← saves (never touched by OTA)
+```
+
+## Host tests (no DEVKITPRO)
+
+```bash
+cd native/switch-ota-launcher
+make host-test
+```
+
+## Switch build (DEVKITPRO)
+
+Needs `DEVKITPRO` with packages roughly:
+
+```bash
+(dkp-)pacman -S --needed switch-curl switch-mbedtls switch-zlib switch-zziplib
+# or: bash scripts/switch/install_devkitpro_deps.sh
+```
+
+```bash
+export DEVKITPRO=/opt/devkitpro   # typical
+cd native/switch-ota-launcher
+make
+# → gen1recomp.nro
+```
+
+Or from repo root:
+
+```bash
+scripts/switch/build_ota_launcher.sh
+```
+
+Docker fallback uses the same pin as fused builds (`scripts/switch/dkp-docker.image`).
+
+## Packaging
+
+`scripts/switch/pack_sd_zip.sh GAME_NRO VERSION OUT_ZIP LAUNCHER_NRO` writes both
+NROs into the SD zip. That zip is also the OTA download asset (unified).
+Manifest: `scripts/switch/ota_launcher.manifest`.
+
+## Status / known gaps
+
+- Zip extraction uses `switch-zziplib` (`ota_unzip.c`) on device.
+- OTA replaces launcher + game from the unified zip (NACP versions stay aligned).
+- Sphaira HOME forwarders cache metadata until reinstalled (see docs/switch-install.md).
+- Install toolchain deps once: `bash scripts/switch/install_devkitpro_deps.sh`