feat(flatpak): add Flatpak manifest for Reticulum MeshChatX including build options and runtime configuration

flatpak.json

@@ -0,0 +1,41 @@
+{
+  "app-id": "com.sudoivan.reticulummeshchatx",
+  "runtime": "org.freedesktop.Platform",
+  "runtime-version": "24.08",
+  "sdk": "org.freedesktop.Sdk",
+  "sdk-extensions": [
+    "org.freedesktop.Sdk.Extension.node20"
+  ],
+  "build-options": {
+    "env": {
+      "PYTHON": "/usr/bin/python3"
+    }
+  },
+  "command": "reticulum-meshchatx",
+  "finish-args": [
+    "--share=network",
+    "--socket=wayland",
+    "--socket=x11",
+    "--socket=pulseaudio",
+    "--device=all",
+    "--filesystem=home",
+    "--filesystem=host",
+    "--talk-name=org.freedesktop.NetworkManager",
+    "--talk-name=org.freedesktop.secrets"
+  ],
+  "modules": [
+    {
+      "name": "reticulum-meshchatx",
+      "buildsystem": "simple",
+      "build-commands": [
+        "bash flatpak-build.sh"
+      ],
+      "sources": [
+        {
+          "type": "dir",
+          "path": "."
+        }
+      ]
+    }
+  ]
+}