Add Gitea self-hosted git/CI/registry to replace GitHub

Deploy Gitea via Helm with dedicated CloudNativePG database,
in-cluster Actions runner (DinD), and built-in container registry.
ArgoCD repoURLs updated to use in-cluster Gitea SSH. Preview
ApplicationSet switched from GitHub PR generator to Gitea PR
generator. App images now pull from gitea.coreworlds.io registry.

Remaining setup after deploy: seal runner token, ArgoCD API token,
and registry pull secret once Gitea is running. Add ArgoCD deploy
key to Gitea repo settings.

.gitea/workflows/deploy-production.yaml

@@ -0,0 +1,59 @@
+name: Deploy Production
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: pnpm/action-setup@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: pnpm
+
+      - run: pnpm install --frozen-lockfile
+
+      - name: Determine changed apps
+        id: changes
+        run: |
+          APPS=$(pnpm turbo build --filter='...[HEAD~1]' --dry-run=json | jq -r '[.packages[] | select(startswith("@homelab/")) | sub("@homelab/";"") ] | join(",")')
+          echo "apps=$APPS" >> "$GITHUB_OUTPUT"
+
+      - name: Build and push images
+        if: steps.changes.outputs.apps != ''
+        run: |
+          echo "${{ secrets.GITEA_TOKEN }}" | docker login gitea.coreworlds.io -u ${{ gitea.actor }} --password-stdin
+          IFS=',' read -ra APPS <<< "${{ steps.changes.outputs.apps }}"
+          for app in "${APPS[@]}"; do
+            docker build \
+              -t gitea.coreworlds.io/julia/homelab-${app}:${{ gitea.sha }} \
+              -t gitea.coreworlds.io/julia/homelab-${app}:latest \
+              apps/${app}
+            docker push gitea.coreworlds.io/julia/homelab-${app}:${{ gitea.sha }}
+            docker push gitea.coreworlds.io/julia/homelab-${app}:latest
+          done
+
+      - name: Update image tags in production overlay
+        if: steps.changes.outputs.apps != ''
+        run: |
+          IFS=',' read -ra APPS <<< "${{ steps.changes.outputs.apps }}"
+          for app in "${APPS[@]}"; do
+            cd apps/${app}/k8s/overlays/production
+            kustomize edit set image gitea.coreworlds.io/julia/homelab-${app}=gitea.coreworlds.io/julia/homelab-${app}:${{ gitea.sha }}
+            cd -
+          done
+
+      - name: Commit image tag updates
+        if: steps.changes.outputs.apps != ''
+        run: |
+          git config user.name "gitea-actions[bot]"
+          git config user.email "gitea-actions[bot]@coreworlds.io"
+          git add apps/*/k8s/overlays/production/
+          git diff --staged --quiet || git commit -m "deploy: update production images to ${{ gitea.sha }}"
+          git push