chore: add LICENSES directory, REUSE.toml, and REUSE compliance workflow

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: szaimen <42591237+szaimen@users.noreply.github.com>

.github/workflows/reuse.yml

@@ -0,0 +1,27 @@
+# This workflow is provided via the organization template repository
+#
+# https://github.com/nextcloud/.github
+# https://docs.github.com/en/actions/learn-github-actions/sharing-workflows-with-your-organization
+
+# SPDX-FileCopyrightText: 2022 Free Software Foundation Europe e.V. <https://fsfe.org>
+#
+# SPDX-License-Identifier: CC0-1.0
+
+name: REUSE Compliance Check
+
+on: [pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  reuse-compliance-check:
+    runs-on: ubuntu-latest-low
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: REUSE Compliance Check
+        uses: fsfe/reuse-action@676e2d560c9a403aa252096d99fcab3e1132b0f5 # v6.0.0