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/include/ota_fs.h

@@ -0,0 +1,32 @@
+#ifndef GEN1_OTA_FS_H
+#define GEN1_OTA_FS_H
+
+#include "ota_protocol.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Read installed game version from sibling version.txt or NRO nacp-less stamp file.
+ * Expects switch/gen1recomp/version.txt containing X.Y.Z. Returns 0 on success. */
+int ota_fs_read_installed_version(const char *install_dir, char *out, size_t out_len);
+
+/* SHA-256 hex (lowercase) of file. Returns 0 on success. */
+int ota_fs_sha256_file(const char *path, char *out_hex, size_t out_len);
+
+/* Apply verified temp payload (extracted game NRO) using atomic plan. Returns 0 on success. */
+int ota_fs_atomic_replace_game(const char *install_dir, const char *verified_game_nro,
+                               char *err, size_t err_len);
+
+/* Atomically replace any named NRO under install_dir (copy→.part→rename). */
+int ota_fs_atomic_replace_nro(const char *install_dir, const char *nro_name,
+                              const char *verified_nro, char *err, size_t err_len);
+
+/* Hand off to game NRO via envSetNextLoad (Switch) or no-op stub (host). */
+int ota_fs_handoff_to_game(const char *game_nro_path, char *err, size_t err_len);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif