fix(design): code-reviewer polish — dedupe tag-mitre recipe, drop dead boxShadow tokens, cover StatusBadge classes

F1: MitreTechniqueTag inline classes replaced with className="tag-mitre gap-xxs"
    (index.css .tag-mitre is now the single source of truth for technique tags).
F2: boxShadow block removed from tailwind.config.ts — no component referenced
    shadow-soft-lift / shadow-floating / *-dark; DESIGN.md §Don'ts prohibits shadows.
F4: StatusBadge.test.tsx gains 3 class assertions (bg-warn-soft / bg-primary-soft / bg-cloud)
    mirroring SimulationStatusBadge.test.tsx pattern. Test count: 136 → 139.

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

frontend/src/components/MitreTechniqueTag.tsx

@@ -22,7 +22,7 @@ export function MitreTechniqueTag({
     <span
       data-testid="mitre-technique-tag"
       title={`${technique.id} — ${technique.name}`}
-      className="inline-flex items-center gap-xxs bg-primary-soft text-primary-deep rounded-none border border-primary-soft px-sm py-xxs text-[13px] font-mono"
+      className="tag-mitre gap-xxs"
     >
       {technique.id}
       {!disabled && (