Audit page blank when plan lacks Audit

Opening /audit (or a shared /audit/events/:id link) in an org whose plan has neither `audit_enabled` nor `session_transcripts_enabled` renders an empty main area (only a divider): no tabs, no message. /sessions in the same org correctly shows "Not on your plan — Your plan doesn't include Session transcripts. See plans". Seen on prod (v1.2.4873) as the TimeSaver org member, 2026-10-27. Requirements: - When `AuditPage` has no visible tab because of the plan, show the same "Not on your plan" panel `RequirePlanSwitch` shows (apps/web/src/lib/planSwitches.tsx), naming Audit. - When no tab is visible for a permission reason, show the console's usual no-access state rather than a blank page. Out of scope: changing which tabs a plan or role unlocks; the sidebar gate. Done means: - A unit test renders AuditPage with both plan switches off and asserts the "Not on your plan" panel. - Visual check on the live stack at desktop width of /audit with both switches off.

AuditPage with no offered tab now shows "Not on your plan" (naming Audit) or redirects to /no-access for permission; unit test + desktop visual check done (panel renders cleanly). Quick gate green; PR #7146 queued to merge lane. Memory: none applied.