feat(apple): native SwiftUI app for iOS and macOS

Add a native SwiftUI VniDrop app (Send/Receive/Settings) talking to the
Rust core via generated UniFFI Swift bindings, plus the uniffi-bindgen
helper crate. iOS uses a TabView, macOS a NavigationSplitView sidebar.

apple/scripts/build-core.sh

@@ -0,0 +1,104 @@
+#!/usr/bin/env bash
+#
+# Builds the VniDrop Rust core for Apple platforms and produces:
+#   - apple/VnidropCore/vnidrop.xcframework   (static libs for device/sim/macOS)
+#   - apple/VnidropCore/Sources/VnidropCore/Vnidrop.swift  (generated bindings)
+#
+# The Rust crate (crates/vnidrop) is NOT modified. Bindings are generated in
+# UniFFI library mode from the compiled staticlib, so the Swift surface always
+# matches the scaffolding baked into the library.
+#
+# Usage: apple/scripts/build-core.sh [debug|release]   (default: release)
+set -euo pipefail
+
+# Default to debug: the workspace `[profile.release]` uses thin LTO, which the
+# current macOS toolchain miscompiles into corrupt host proc-macro dylibs
+# ("mis-aligned LINKEDIT string pool"), breaking any release cross-compile. Debug
+# static libs are correct and adequate for development and the simulator. For a
+# release build, pass `release` AND disable LTO for proc-macros/build scripts via
+# CARGO_PROFILE_RELEASE_BUILD_OVERRIDE_LTO=false in a Cargo.toml profile — see the
+# package README. The Rust crate itself is never modified.
+PROFILE="${1:-debug}"
+case "$PROFILE" in
+	debug) CARGO_PROFILE_FLAG="" ;;
+	release) CARGO_PROFILE_FLAG="--release" ;;
+	*) echo "profile must be debug or release" >&2; exit 1 ;;
+esac
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+APPLE_DIR="$REPO_ROOT/apple"
+PKG_DIR="$APPLE_DIR/VnidropCore"
+GEN_DIR="$PKG_DIR/Sources/VnidropCore"
+TARGET_DIR="$REPO_ROOT/target"
+BUILD_DIR="$APPLE_DIR/.build-core"
+
+# Match the iOS deployment target used by the Gobley config in shared/build.gradle.kts.
+export IPHONEOS_DEPLOYMENT_TARGET="${IPHONEOS_DEPLOYMENT_TARGET:-16.0}"
+export MACOSX_DEPLOYMENT_TARGET="${MACOSX_DEPLOYMENT_TARGET:-13.0}"
+
+# The workspace `[profile.dev] strip = "debuginfo"` corrupts host proc-macro
+# dylibs on the current Apple toolchain ("mis-aligned LINKEDIT string pool"),
+# which breaks compilation. The Gobley Xcode run-script uses the same override.
+# This never touches the Rust crate — it only changes how the build is invoked.
+export CARGO_PROFILE_DEV_STRIP=none
+
+IOS_TARGET="aarch64-apple-ios"
+SIM_ARM_TARGET="aarch64-apple-ios-sim"
+SIM_X64_TARGET="x86_64-apple-ios"
+MAC_TARGET="aarch64-apple-darwin"
+
+echo "==> Building vnidrop staticlib ($PROFILE) for Apple targets"
+for t in "$IOS_TARGET" "$SIM_ARM_TARGET" "$SIM_X64_TARGET" "$MAC_TARGET"; do
+	echo "    - $t"
+	rustup target add "$t" >/dev/null 2>&1 || true
+	( cd "$REPO_ROOT" && cargo build -p vnidrop --target "$t" $CARGO_PROFILE_FLAG )
+done
+
+LIB_SUBDIR="$PROFILE"
+[ "$PROFILE" = "debug" ] && LIB_SUBDIR="debug"
+
+MAC_LIB="$TARGET_DIR/$MAC_TARGET/$LIB_SUBDIR/libvnidrop.a"
+IOS_LIB="$TARGET_DIR/$IOS_TARGET/$LIB_SUBDIR/libvnidrop.a"
+
+# Fresh scratch dir for the bindgen output and the universal simulator lib.
+rm -rf "$BUILD_DIR"
+mkdir -p "$BUILD_DIR"
+
+# Combine the two simulator architectures into one universal static library so
+# the xcframework works on both Apple Silicon and Intel simulators.
+SIM_LIB="$BUILD_DIR/libvnidrop-sim.a"
+lipo -create \
+	"$TARGET_DIR/$SIM_ARM_TARGET/$LIB_SUBDIR/libvnidrop.a" \
+	"$TARGET_DIR/$SIM_X64_TARGET/$LIB_SUBDIR/libvnidrop.a" \
+	-output "$SIM_LIB"
+
+echo "==> Generating Swift bindings (library mode)"
+( cd "$REPO_ROOT" && cargo run -p uniffi-bindgen -- generate \
+	--library "$MAC_LIB" \
+	--language swift \
+	--out-dir "$BUILD_DIR" )
+
+# UniFFI emits: Vnidrop.swift, vnidropFFI.h, vnidropFFI.modulemap
+mkdir -p "$GEN_DIR"
+cp "$BUILD_DIR/Vnidrop.swift" "$GEN_DIR/Vnidrop.swift"
+
+# Assemble a headers dir the xcframework can carry as the FFI module.
+HEADERS_DIR="$BUILD_DIR/headers"
+mkdir -p "$HEADERS_DIR"
+cp "$BUILD_DIR/vnidropFFI.h" "$HEADERS_DIR/"
+# The xcframework module map must be named module.modulemap.
+cp "$BUILD_DIR/vnidropFFI.modulemap" "$HEADERS_DIR/module.modulemap"
+
+echo "==> Assembling xcframework"
+XCFRAMEWORK="$PKG_DIR/vnidrop.xcframework"
+rm -rf "$XCFRAMEWORK"
+xcodebuild -create-xcframework \
+	-library "$IOS_LIB" -headers "$HEADERS_DIR" \
+	-library "$SIM_LIB" -headers "$HEADERS_DIR" \
+	-library "$MAC_LIB" -headers "$HEADERS_DIR" \
+	-output "$XCFRAMEWORK"
+
+echo "==> Done."
+echo "    xcframework: $XCFRAMEWORK"
+echo "    bindings:    $GEN_DIR/Vnidrop.swift"