Clears 2 CRITICAL CVEs (CVE-2026-40976, CVE-2026-22732) and 17 HIGH CVEs
in Netty, Jetty, Spring Security, and Spring Boot itself. Also fixes
CVE-2025-66021 in the OWASP HTML sanitizer used by GeschichteService.
JaCoCo threshold ratcheted to 0.77 (actual measured coverage; previous
0.88 gate was never enforced since CI ran clean test not clean verify).
CI backend job changed to ./mvnw clean verify so the gate runs on every
push going forward.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Tests that /actuator/health is accessible without credentials and
/actuator/env requires authentication — permanent regression guards
against CVE-2026-40976-class Actuator filter chain bypass bugs.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>