Add CI to build Linux binaries

.github/FUNDING.yml

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+github: HarmonyHoney
+ko_fi: hhoney
+custom:
+  - https://hhoneysoft.itch.io/
+  - https://store.steampowered.com/publisher/HarmonyHoney
+  - https://www.youtube.com/@hhoney7
+
+# Unused by keeping here as a reminder
+patreon: # Replace with a single Patreon username
+open_collective: # Replace with a single Open Collective username
+tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
+community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
+liberapay: # Replace with a single Liberapay username
+issuehunt: # Replace with a single IssueHunt username
+lfx_crowdfunding: # Replace with a single LFX Crowdfunding project-name e.g., cloud-foundry
+polar: # Replace with a single Polar username
+buy_me_a_coffee: # Replace with a single Buy Me a Coffee username
+thanks_dev: # Replace with a single thanks.dev username

.github/workflows/godot-linux.yml

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+name: "Godot Linux"
+on:
+  workflow_dispatch:
+  pull_request:
+  release:
+    types:
+      - released
+
+env:
+  GODOT_VERSION: 3.6
+  EXPORT_NAME: rota-linux
+
+jobs:
+  export:
+    name: Export
+    runs-on: ubuntu-latest
+    container:
+      image: docker.io/smks/godot-ci:3.6
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          lfs: true
+
+      - name: Set up export templates
+        run: |
+          mkdir -v -p ~/.local/share/godot/templates/
+          mv /root/.local/share/godot/templates/${GODOT_VERSION}.stable ~/.local/share/godot/templates/${GODOT_VERSION}.stable
+
+      - name: Export
+        run: |
+          mkdir --verbose --parents ./export/linux
+          godot --no-window --path=./project.godot --export "Linux/X11" ./export/linux/${EXPORT_NAME}.x86_64
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ env.EXPORT_NAME }}
+          path: |
+            export/linux/${{ env.EXPORT_NAME }}.x86_64
+            export/linux/${{ env.EXPORT_NAME }}.pck
+
+  release:
+    name: Release
+    needs: export
+    if: ${{ github.event_name == 'release' }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ env.EXPORT_NAME }}
+
+      - name: Display downloaded files
+        run: ls -R
+
+      - name: Upload to release
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+        run: >-
+          gh release upload '${{ github.ref_name }}' * --repo '${{ github.repository }}'