Shared dashboards are a dead end (tokens minted, no page/endpoint/UI)

Severity: High (parity blocker) · Where: sharing.ts:50,65-104; authz.ts:63-89; views.ts:155-156 Share tokens are minted but handleGetSharedDashboard returns no stats, all stats endpoints require session+membership, and there's no /shared/{token} page or "create share link" UI. Fix: Add a token-scoped read endpoint that bypasses siteAuthGuard, a /shared/{token} page, and UI to mint links.