ci: switch to node:20-slim and fix YAML indentation

Fix CI failure caused by YAML indentation issues and missing SSH client.

Changes:
1. Fix YAML indentation for build-and-deploy step
2. Switch from node:20-alpine to node:20-slim
3. Update SSH installation commands for Debian-based system
4. Add SSH client availability check

Benefits:
- node:20-slim may already include SSH client
- If not, uses apt-get instead of apk for installation
- Better compatibility with deployment tools

This should resolve the 'No pipeline steps available!' error.

.woodpecker.yml

@@ -1,5 +1,5 @@
 variables:
-  - &node_image node:20-alpine
+  - &node_image node:20-slim
 
 steps:
   install-deps:
@@ -112,29 +112,30 @@ steps:
         - dev
 
   build-and-deploy:
-    image: node:20-alpine
-  environment:
-    NODE_ENV: production
-    NEXT_TELEMETRY_DISABLED: 1
-    SSH_PRIVATE_KEY:
-      from_secret: ssh_private_key
-  depends_on:
-    - install-deps
-    - lint
-    - type-check
-  commands:
-    - echo "Installing SSH client"
-    - apk add --no-cache openssh-client rsync
-    - echo "Building production artifacts"
-    - npm run build
-    - echo "Build completed"
-    - ls -la dist/
-    - echo "Deploying to production"
-    - mkdir -p ~/.ssh
-    - echo "$SSH_PRIVATE_KEY" > ~/.ssh/id_rsa
-    - chmod 600 ~/.ssh/id_rsa
-    - echo "Pre-deployment checks"
-    - ssh root@139.155.109.62 "echo 'Server connection OK'"
+    image: *node_image
+    environment:
+      NODE_ENV: production
+      NEXT_TELEMETRY_DISABLED: 1
+      SSH_PRIVATE_KEY:
+        from_secret: ssh_private_key
+    depends_on:
+      - install-deps
+      - lint
+      - type-check
+    commands:
+      - echo "Checking SSH client availability"
+      - which ssh && echo "SSH client found" || echo "Installing SSH client"
+      - apt-get update && apt-get install -y openssh-client rsync
+      - echo "Building production artifacts"
+      - npm run build
+      - echo "Build completed"
+      - ls -la dist/
+      - echo "Deploying to production"
+      - mkdir -p ~/.ssh
+      - echo "$SSH_PRIVATE_KEY" > ~/.ssh/id_rsa
+      - chmod 600 ~/.ssh/id_rsa
+      - echo "Pre-deployment checks"
+      - ssh root@139.155.109.62 "echo 'Server connection OK'"
       - ssh root@139.155.109.62 "df -h | grep -E '/$|/home'"
       - echo "Syncing build artifacts to production server"
       - rsync -avz --delete dist/ root@139.155.109.62:/home/novalon/docker-app/novalon-website/dist/