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)

internal/store/settings.go

@@ -15,6 +15,7 @@ func (s *Store) GetSettings() (Settings, error) {
 		        allowed_volume_paths, wildcard_dns, dns_provider,
 		        cloudflare_api_token, cloudflare_zone_id,
 		        proxy_provider,
+		        traefik_entrypoint, traefik_cert_resolver, traefik_network, traefik_api_url,
 		        backup_enabled, backup_interval_hours, backup_retention_count,
 		        updated_at
 		 FROM settings WHERE id = 1`,
@@ -24,6 +25,7 @@ func (s *Store) GetSettings() (Settings, error) {
 		&st.AllowedVolumePaths, &wildcardDNS, &st.DNSProvider,
 		&st.CloudflareAPIToken, &st.CloudflareZoneID,
 		&st.ProxyProvider,
+		&st.TraefikEntrypoint, &st.TraefikCertResolver, &st.TraefikNetwork, &st.TraefikAPIURL,
 		&backupEnabled, &st.BackupIntervalHours, &st.BackupRetentionCount,
 		&st.UpdatedAt)
 	if err != nil {
@@ -53,6 +55,7 @@ func (s *Store) UpdateSettings(st Settings) error {
 			allowed_volume_paths=?, wildcard_dns=?, dns_provider=?,
 			cloudflare_api_token=?, cloudflare_zone_id=?,
 			proxy_provider=?,
+			traefik_entrypoint=?, traefik_cert_resolver=?, traefik_network=?, traefik_api_url=?,
 			backup_enabled=?, backup_interval_hours=?, backup_retention_count=?,
 			updated_at=?
 		 WHERE id = 1`,
@@ -62,6 +65,7 @@ func (s *Store) UpdateSettings(st Settings) error {
 		st.AllowedVolumePaths, wildcardDNS, st.DNSProvider,
 		st.CloudflareAPIToken, st.CloudflareZoneID,
 		st.ProxyProvider,
+		st.TraefikEntrypoint, st.TraefikCertResolver, st.TraefikNetwork, st.TraefikAPIURL,
 		backupEnabled, st.BackupIntervalHours, st.BackupRetentionCount,
 		st.UpdatedAt,
 	)