fix(ci): replace docker-compose v1 with docker compose v2

The act runner does not have the standalone docker-compose binary.
Replace both occurrences with the v2 plugin syntax (space instead of hyphen).
Closes #3

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -64,12 +64,12 @@ jobs:
 
       # ── Infrastructure ──────────────────────────────────────────────────────
       - name: Start DB and MinIO
-        run: docker-compose up -d db minio create-buckets
+        run: docker compose up -d db minio create-buckets
 
       - name: Wait for DB to be ready
         run: |
           timeout 30 bash -c \
-            'until docker-compose exec -T db pg_isready -U archive_user; do sleep 2; done'
+            'until docker compose exec -T db pg_isready -U archive_user; do sleep 2; done'
 
       # ── Backend ─────────────────────────────────────────────────────────────
       - uses: actions/setup-java@v4