ci: Switch to Woodpecker CI pipeline

Replaces Gitea Actions with Woodpecker CI config.

Pipeline:
- CI: typecheck backend, build all 3 frontends (all branches)
- CD: build 4 Docker images, deploy to k8s (master only)

Required secrets in Woodpecker:
- registry_username
- registry_password
- kubeconfig_data (base64 encoded)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

@@ -37,6 +37,10 @@ npm-debug.log*
 # Local storage (runtime data, not source)
 backend/storage/
 
+# Product images (crawled data, not source)
+backend/public/images/products/
+backend/public/images/brands/
+
 # Vite cache
 **/node_modules/.vite/