refactor: remove standalone proxies, add Traefik provider with Docker labels

Standalone proxy removal:
- Delete store, API handlers, proxy manager, health monitor, validator, hints
- Delete frontend pages (proxies list, create, edit) and components (ProxyCard, ProxyForm, ProxyFilter, ProxyGroup, ValidationChecklist)
- Remove proxy routes from router, nav items, dashboard references
- Clean up SystemHealthCard to remove proxy section

Traefik provider:
- Add TraefikProvider implementing proxy.Provider via Docker labels
- ContainerLabels() returns traefik.enable, router rule, entrypoints, service port, TLS cert resolver, docker network
- ConfigureRoute() returns router name (labels handle routing at container creation)
- DeleteRoute() is no-op (container removal auto-deregisters)
- Ping() checks Traefik API health (optional)
- Wire ContainerLabels into deployer (executeDeploy + blueGreenDeploy)
- Add Traefik settings: entrypoint, cert_resolver, network, api_url
- Add traefik option to proxy provider selector in settings UI
- Show conditional Traefik config fields
- Add i18n keys (EN + RU)

.claude/settings.json

@@ -10,7 +10,8 @@
       "Bash(go vet:*)",
       "Bash(git checkout:*)",
       "Bash(git stash:*)",
-      "Bash(echo \"EXIT: $?\")"
+      "Bash(echo \"EXIT: $?\")",
+      "Bash(./scripts/dev-server.sh)"
     ],
     "additionalDirectories": [
       "C:\\Users\\Alexei\\Documents\\docker-watcher\\internal",