fix(rtl): anchor floating menus with logical start/end instead of left/right

Popovers and dropdown menus across the app (sub-address helper, calendar
toolbar/color pickers, contact/template/attachment menus, rich text editor
color and table pickers, unsubscribe confirmation, composer send menu)
were anchored with physical `left-0`/`right-0`. In RTL locales those
don't flip with the trigger, so the menu detaches from the button that
opened it. Switched to Tailwind's logical `start-0`/`end-0` (and the
matching `rounded-s-*`/`rounded-e-*` corners on hover-action overlays)
so they mirror correctly for RTL locales (ar, he, fa) while staying
identical in LTR.

components/email/unsubscribe-banner.tsx

@@ -147,7 +147,7 @@ export function UnsubscribeBanner({
         {showConfirm && isDesktop && (
           <div
             ref={popoverRef}
-            className="absolute top-full left-0 mt-1 z-50 bg-background border border-border rounded-lg shadow-lg p-3 min-w-[220px]"
+            className="absolute top-full start-0 mt-1 z-50 bg-background border border-border rounded-lg shadow-lg p-3 min-w-[220px]"
           >
             <p className="text-sm text-foreground mb-2">
               {t('email_viewer.unsubscribe_banner.confirm_title')}