Add plugin upload workflow and related enhancements

- Introduced a new upload workflow for the Atlas plugin to Roblox using Lune and OpenCloud.
- Added `UploadDetails.json` to store plugin metadata.
- Updated `build.rs` to include `UploadDetails.json` in the plugin snapshot.
- Enhanced `plugin.project.json` to reference the new `UploadDetails`.
- Added a new submodule for `opencloud-execute` to facilitate plugin uploads.
- Created scripts for publishing the plugin via both PowerShell and Bash.
- Updated GitHub Actions workflow to include steps for installing Rokit and uploading the plugin.

These changes aim to streamline the plugin release process and improve integration with Roblox's marketplace.

scripts/publish-plugin.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+# Build and publish the Atlas plugin to the Creator Store via OpenCloud.
+# Loads env vars from .env file in the repo root.
+# Required .env vars: PLUGIN_UPLOAD_TOKEN, PLUGIN_CI_UNIVERSE_ID, PLUGIN_CI_PLACE_ID
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ENV_FILE="$SCRIPT_DIR/../.env"
+
+if [ -f "$ENV_FILE" ]; then
+    set -a
+    source "$ENV_FILE"
+    set +a
+fi
+
+if [ -z "${PLUGIN_UPLOAD_TOKEN:-}" ]; then
+    echo "Error: PLUGIN_UPLOAD_TOKEN not set. Add it to .env or set as env var." >&2
+    exit 1
+fi
+
+export RBX_API_KEY="$PLUGIN_UPLOAD_TOKEN"
+export RBX_UNIVERSE_ID="${PLUGIN_CI_UNIVERSE_ID:-}"
+export RBX_PLACE_ID="${PLUGIN_CI_PLACE_ID:-}"
+
+echo "Building and uploading plugin..."
+lune run upload-plugin Atlas.rbxm