feat(pkg): add flatpak build manifest and workflow (#75)

* feat(pkg): add flatpak build manifest

* feat(pkg): add flatpak build step to release workflow

* fix(pkg): flatpak build script failing due to absence of zsh

* fix: flatpak manifest pcsc build error

* feat(pkg): build flatpaks parallel to other workflow steps

* fix(pkg): windows installation binaries glob in workflow

* chore(pkg): change appimage naming in release workflow

.github/scripts/build_flatpak.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+set -e
+
+PLATFORM=$1
+VERSION=${version:-"0.0.0"}
+
+if [[ "$PLATFORM" == "ubuntu-24.04-arm" ]]; then
+    ARCH="arm64"
+    FLATPAK_ARCH="aarch64"
+else
+    ARCH="x86-64"
+    FLATPAK_ARCH="x86_64"
+fi
+
+echo "Building Flatpak for architecture: $FLATPAK_ARCH (Release: $VERSION)"
+
+flatpak remote-add --user --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
+
+flatpak install --user -y flathub \
+    org.freedesktop.Platform//25.08 \
+    org.freedesktop.Sdk//25.08 \
+    org.freedesktop.Sdk.Extension.rust-stable//25.08
+
+flatpak-builder --user --arch="${FLATPAK_ARCH}" --force-clean --repo=repo build-dir .github/manifests/in.suyogtandel.picoforge.json
+
+flatpak build-bundle repo "picoforge_${VERSION}_${ARCH}.flatpak" in.suyogtandel.picoforge