Add Gitea Actions CI: test + build/push to registry

Matches the pattern used by Dashboard and Zbrane-Reiner-Web -- release
branch pushes :latest, devel pushes :devel. Requires a REGISTRY_TOKEN
secret on this repo (Settings -> Actions -> Secrets), same as those two.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WDDfSVPh5pgNe7TRpZUgJA

.gitea/workflows/ci.yml

@@ -0,0 +1,66 @@
+name: CI
+
+# Spustí se při pushi do devel/release a jde i ručně spustit z GUI.
+on:
+  push:
+    branches: [devel, release]
+  workflow_dispatch:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Instalace Poetry
+        run: pip install poetry==2.4.1
+
+      - name: Instalace závislostí (vč. dev skupiny)
+        run: poetry install --no-interaction
+
+      - name: Ruff
+        run: poetry run ruff check .
+
+      - name: Mypy
+        run: poetry run mypy src
+
+      - name: Testy
+        run: poetry run pytest -q
+
+  build-and-push:
+    needs: test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      # Docker jméno musí být malými písmeny (Honza/Restreamer -> honza/restreamer)
+      - name: Název image
+        run: |
+          echo "IMAGE=gitea.doubynet.eu/$(echo '${{ github.repository }}' \
+            | tr '[:upper:]' '[:lower:]')" >> "$GITHUB_ENV"
+
+      # release -> latest (produkce), devel -> devel (staging)
+      - name: Značka podle větve
+        run: |
+          if [ "${{ github.ref_name }}" = "release" ]; then
+            echo "MOVING_TAG=latest" >> "$GITHUB_ENV"
+          else
+            echo "MOVING_TAG=devel" >> "$GITHUB_ENV"
+          fi
+
+      - name: Přihlášení do Gitea registry
+        run: |
+          echo '${{ secrets.REGISTRY_TOKEN }}' \
+            | docker login gitea.doubynet.eu -u '${{ github.actor }}' --password-stdin
+
+      - name: Build image
+        run: docker build -t "$IMAGE:$MOVING_TAG" -t "$IMAGE:${{ github.sha }}" .
+
+      - name: Push image
+        run: |
+          docker push "$IMAGE:$MOVING_TAG"
+          docker push "$IMAGE:${{ github.sha }}"