Add optimized multi-platform release CI/CD pipeline.

Split Windows builds into shared x64 prep and arch-specific packaging, add comprehensive caching, verification scripts, and a PR smoke workflow.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/ci-package-windows-release.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ARCH="${1:?usage: ci-package-windows-release.sh <x64|arm64>}"
+
+export FROMCHAT_PACKAGING_JDK="${JAVA_HOME}"
+export FROMCHAT_SKIP_RUST_BUILD=1
+
+GRADLE_ARGS=(
+  :app:desktop:createReleaseDistributable
+  :app:desktop:patchWindowsJpackageReleaseIcon
+  :app:desktop:packSetupOnly
+  "-PdesktopArch=$ARCH"
+  --no-daemon
+  --console=plain
+)
+
+if [[ "$ARCH" == "arm64" ]]; then
+  GRADLE_ARGS+=("-PwindowsArm64")
+fi
+
+./gradlew "${GRADLE_ARGS[@]}"