ci: remove container: directive, use setup actions for Docker mode

.gitea/workflows/ci.yaml

@@ -12,11 +12,14 @@ jobs:
   backend:
     name: Backend (.NET)
     runs-on: linux
-    container:
-      image: mcr.microsoft.com/dotnet/sdk:10.0
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
+
+      - name: Setup .NET SDK
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '10.0.x'
 
       - name: Restore
         run: dotnet restore backend/Nexus.Api.csproj
@@ -32,11 +35,14 @@ jobs:
   frontend:
     name: Frontend (Vue/TS)
     runs-on: linux
-    container:
-      image: node:24-alpine
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '24'
 
       - name: Setup pnpm
         run: |
@@ -62,7 +68,7 @@ jobs:
     if: github.ref == 'refs/heads/main'
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Check for .env leaks
         run: |