Add i18n, branding, user management, health checks, and cleanup for deployment

- Multi-language support (EN/DE) with i18n engine and language files
- Configurable branding (name, subtitle, logo) in Settings
- Global default language and per-user language preference
- User management router with CRUD endpoints
- Customer status sync on start/stop/restart
- Health check fixes: derive status from container state, remove broken wget healthcheck
- Caddy reverse proxy and dashboard env templates for customer stacks
- Updated README with real hardware specs, prerequisites, and new features
- Removed .claude settings (JWT tokens) and build artifacts from tracking
- Updated .gitignore for .claude/ and Windows artifacts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

templates/Caddyfile.j2

@@ -0,0 +1,36 @@
+{
+	auto_https off
+}
+
+:80 {
+	# Embedded IdP OAuth2/OIDC endpoints
+	handle /oauth2/* {
+		reverse_proxy netbird-kunde{{ customer_id }}-management:80
+	}
+
+	# NetBird Management API + gRPC
+	handle /api/* {
+		reverse_proxy netbird-kunde{{ customer_id }}-management:80
+	}
+	handle /management.ManagementService/* {
+		reverse_proxy netbird-kunde{{ customer_id }}-management:80 {
+			transport http {
+				versions h2c
+			}
+		}
+	}
+
+	# NetBird Signal gRPC
+	handle /signalexchange.SignalExchange/* {
+		reverse_proxy netbird-kunde{{ customer_id }}-signal:80 {
+			transport http {
+				versions h2c
+			}
+		}
+	}
+
+	# Default: NetBird Dashboard
+	handle {
+		reverse_proxy netbird-kunde{{ customer_id }}-dashboard:80
+	}
+}