feat: Add flatpak build tools

flatpak/org.xetibo.ReSet.json

@@ -0,0 +1,41 @@
+{
+  "app-id": "org.xetibo.ReSet",
+  "runtime": "org.gnome.Platform",
+  "runtime-version": "45",
+  "sdk": "org.gnome.Sdk",
+  "sdk-extensions": ["org.freedesktop.Sdk.Extension.rust-stable"],
+  "command": "reset",
+  "finish-args": [
+    "--socket=session-bus",
+    "--share=ipc",
+    "--socket=fallback-x11",
+    "--socket=wayland",
+    "--device=dri"
+  ],
+  "build-options": {
+    "append-path": "/usr/lib/sdk/rust-stable/bin"
+  },
+  "modules": [
+    {
+      "name": "reset",
+      "buildsystem": "simple",
+      "build-options": {
+        "env": {
+          "CARGO_HOME": "/run/build/reset/cargo"
+        }
+      },
+      "build-commands": [
+        "cargo --offline fetch --manifest-path Cargo.toml --verbose",
+        "cargo --offline build --release --verbose",
+        "install -Dm755 ./target/release/reset -t /app/bin/"
+      ],
+      "sources": [
+        {
+          "type": "dir",
+          "path": ".."
+        },
+        "cargo-sources.json"
+      ]
+    }
+  ]
+}