Add github actions, license file, security.md

.github/workflows/ci.yml

@@ -0,0 +1,42 @@
+---
+name: ci
+
+on: [push, pull_request, merge_group]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    container:
+      image: registry.fedoraproject.org/fedora:37
+    steps:
+      - run: dnf install -y git make
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Install dependencies
+        run: |
+          make test-deps
+      - name: Run linters
+        run: |
+          git config --global --add safe.directory '*'
+          make lint
+  build-rpm:
+    runs-on: ubuntu-latest
+    container:
+      image: registry.fedoraproject.org/fedora:37
+    steps:
+      - run: dnf install -y git make
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Install dependencies
+        run: |
+          make build-deps
+      - name: Build RPM
+        run: |
+          git config --global --add safe.directory '*'
+          make build-rpm
+      - name: Check reproducibility
+        run: |
+          make test-deps
+          make reprotest

.github/workstation-ci.yml

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+# for <https://github.com/freedomofpress/securedrop-workstation-ci>
+qubes: "4.2"