fix(settings): lock site context to current URL, rename Workspace to Organization

- Site context is locked to the site from the current URL — no dropdown
  switcher. If not on a site page, defaults to Organization context.
- Renamed "Workspace" to "Organization" in all user-facing text.
- Removed unused CaretDown import and dropdown state.

components/settings/unified/tabs/WorkspaceMembersTab.tsx

@@ -82,7 +82,7 @@ export default function WorkspaceMembersTab() {
       <div className="flex items-center justify-between">
         <div>
           <h3 className="text-base font-semibold text-white mb-1">Members</h3>
-          <p className="text-sm text-neutral-400">{members.length} member{members.length !== 1 ? 's' : ''} in your workspace.</p>
+          <p className="text-sm text-neutral-400">{members.length} member{members.length !== 1 ? 's' : ''} in your organization.</p>
         </div>
         {canManage && !showInvite && (
           <Button onClick={() => setShowInvite(true)} variant="primary" className="text-sm gap-1.5">