fix(subscription): clear critique P0 + P1 + part of P2

Three issues from the post-PRODUCT.md /impeccable critique pass:

P0 — backdrop-blur-xl shipped to mobile on the two hero cards
(SubscriptionCardActive + Subscription detail). DESIGN.md
'Mobile-Without-Blur Rule' restricts backdrop-blur to ≥1024px.
Gate with lg: prefix so phones (half the audience) get the opaque
surface and skip the scroll-jank-inducing GPU blur layer.

P1 — Two destructive device-deletion sites still called the bare
browser confirm(). The codebase already imports useDestructiveConfirm
and uses it correctly for revoke (line 484). Bring the all-devices
and per-device delete paths onto the same platform-aware path, so
inside Telegram the user gets the native destructive popup with
haptic + theme, and on web they get the inline destructive panel.

P2 (partial) — Removed the decorative ambient radial-gradient halo
behind the Subscription detail hero card and the trial-shimmer border
overlay. Same chrome was distilled out of SubscriptionCardActive
earlier in this branch; the rationale is identical (zone/accent hue
leaking into pure decoration violates DESIGN.md Tunable-but-Scarce
+ Status-Hue Lockout rules). Trial state is conveyed by the header
badge.

src/components/dashboard/SubscriptionCardActive.tsx

@@ -72,7 +72,7 @@ export default function SubscriptionCardActive({
 
   return (
     <div
-      className="relative overflow-hidden rounded-3xl backdrop-blur-xl"
+      className="relative overflow-hidden rounded-3xl lg:backdrop-blur-xl"
       style={{
         background: g.cardBg,
         border: subscription.is_trial