The model plaza route already supports public access, but both built-in /home headers omit its entry. Add the link to compact and default headers while keeping the existing feature and authentication settings authoritative, then cover the visibility matrix with focused component tests.
Constraint: Keep the change frontend-only and preserve router-owned access control
Rejected: Add the link to AppHeader only | /home renders its own headers and never mounts AppHeader
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: Keep the model plaza entry gated by the existing opt-in flag and require-auth setting
Tested: HomeView focused Vitest, full frontend Vitest (223 files / 1554 tests), ESLint, vue-tsc, production build
Not-tested: Manual browser click-through against a running backend
Related: #5524
