Subscription Page Change Dialog Polish

Found while checking Task 8197's Subscription page on the live stack. - When the org's plan is the only active plan, the Change dialog lists just "Free · Current plan" — a dead end. Hide Change (keep a Contact us link) when no other plan can be chosen. - The Change dialog's footer puts Close and Contact us side by side as equal-weight links; make Contact us read as a link inside the body ("Need another plan? Contact us") so Close is the only footer action. - The Limits table has no hint which limit the current plan is close to; highlight a row at or over its cap (e.g. Users 1 / 1). Out of scope: plan model, enforcement, billing/Stripe flows. Done means: each item visible on the live Subscription page at desktop and ≤480px; web unit tests for the Subscription page green.

Subscription page: Change is hidden (Contact us offered) when no other plan is listed, Contact us is a link in the dialog body, and limits at or over their cap are marked. Quick gate green, page tests 36/36, visual check done at desktop and 390px. PR #6362 queued in the merge lane. Follow-up draft #8225 filed. Memory: none applied.