feat: integrate client and server sharing workflows

.woodpecker/release-backend.yml

@@ -0,0 +1,29 @@
+when:
+  - event: tag
+    ref: refs/tags/v*
+
+steps:
+  release-checks:
+    image: mcr.microsoft.com/dotnet/sdk:10.0
+    commands:
+      - dotnet test server/WebDrop.slnx --configuration Release --verbosity minimal
+
+  validate-release:
+    image: node:24.21.0-alpine3.23
+    commands:
+      - node scripts/check-api-contract.mjs "$CI_COMMIT_TAG"
+
+  publish-backend:
+    image: woodpeckerci/plugin-docker-buildx:2
+    privileged: true
+    settings:
+      context: .
+      dockerfile: server/Dockerfile
+      platforms: linux/amd64
+      repo: zot.oeo.one/justme/webdrop-api
+      registry: zot.oeo.one
+      tags: ${CI_COMMIT_TAG}
+      username:
+        from_secret: registry_username
+      password:
+        from_secret: registry_password