Fix deploy: use if/then instead of && to avoid pipefail exit

The Dockerfile check in the while-read loop used `[ -f ... ] && echo`,
which exits non-zero for packages without Dockerfiles. With bash's
pipefail, this killed the entire step. Also remove unused GitHub
workflow copies since CI runs on Gitea only.

.gitea/workflows/deploy-preview.yaml

@@ -20,7 +20,7 @@ jobs:
       - name: Determine changed apps
         id: changes
         run: |
-          APPS=$(pnpm turbo build --filter='...[origin/main]' --dry-run=json | jq -r '[.packages[] | select(startswith("@homelab/")) | sub("@homelab/";"") ] | join(",")' | tr ',' '\n' | while read app; do [ -f "apps/${app}/Dockerfile" ] && echo "$app"; done | paste -sd, -)
+          APPS=$(pnpm turbo build --filter='...[origin/main]' --dry-run=json | jq -r '[.packages[] | select(startswith("@homelab/")) | sub("@homelab/";"") ] | join(",")' | tr ',' '\n' | while read app; do if [ -f "apps/${app}/Dockerfile" ]; then echo "$app"; fi; done | paste -sd, -)
           echo "apps=$APPS" >> "$GITHUB_OUTPUT"
 
       - name: Build and push images

.gitea/workflows/deploy-production.yaml

@@ -36,7 +36,7 @@ jobs:
               APPS="$INPUT"
             fi
           else
-            APPS=$(pnpm turbo build --filter='...[HEAD~1]' --dry-run=json | jq -r '[.packages[] | select(startswith("@homelab/")) | sub("@homelab/";"") ] | join(",")' | tr ',' '\n' | while read app; do [ -f "apps/${app}/Dockerfile" ] && echo "$app"; done | paste -sd, -)
+            APPS=$(pnpm turbo build --filter='...[HEAD~1]' --dry-run=json | jq -r '[.packages[] | select(startswith("@homelab/")) | sub("@homelab/";"") ] | join(",")' | tr ',' '\n' | while read app; do if [ -f "apps/${app}/Dockerfile" ]; then echo "$app"; fi; done | paste -sd, -)
           fi
           echo "apps=$APPS" >> "$GITHUB_OUTPUT"