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/templates/template-form.tsx

@@ -285,7 +285,7 @@ function PlaceholderDropdown({
   return (
     <>
       <div className="fixed inset-0 z-40" onClick={onClose} />
-      <div className="absolute right-0 top-full mt-1 z-50 bg-background border border-border rounded-md shadow-lg min-w-[180px]">
+      <div className="absolute end-0 top-full mt-1 z-50 bg-background border border-border rounded-md shadow-lg min-w-[180px]">
         <div className="p-1">
           {BUILT_IN_PLACEHOLDERS.map((p) => (
             <button