fix(mobile): 44px touch targets for primary call/thread/mod controls (P1)

Deep-audit follow-up. New shared MobileTouchTarget class (@media <=750px ->
minWidth/minHeight 44px) applied via className to the primary interactive
controls folds renders below 44px:
- in-call control bar (7 buttons) + persistent call-status bar (4 buttons)
- thread "N replies" chip
- knock Approve/Deny buttons
- server-ACL entry remove button

folds size variants set only padding (no width/height/min-*), so the class
raises the hit-area floor to 44px with the icon/label staying centered at its
normal size; desktop is untouched (@media-gated). Verified by two review passes
(no distortion, no layout overflow, counts exact).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/room/MembersDrawer.tsx

@@ -30,6 +30,7 @@ import {
 import { MatrixClient, Room, RoomMember } from 'matrix-js-sdk';
 import { useVirtualizer } from '@tanstack/react-virtual';
 import classNames from 'classnames';
+import { MobileTouchTarget } from '../../styles/mobile.css';
 import { Membership } from '../../../types/matrix/room';
 
 import * as css from './MembersDrawer.css';
@@ -460,6 +461,7 @@ export function MembersDrawer({ room, members }: MembersDrawerProps) {
                           variant="Success"
                           radii="300"
                           fill="Soft"
+                          className={MobileTouchTarget}
                           onClick={() => mx.invite(room.roomId, knockMember.userId)}
                         >
                           <Text size="B300">Approve</Text>
@@ -469,6 +471,7 @@ export function MembersDrawer({ room, members }: MembersDrawerProps) {
                           variant="Critical"
                           radii="300"
                           fill="Soft"
+                          className={MobileTouchTarget}
                           onClick={() => mx.kick(room.roomId, knockMember.userId)}
                         >
                           <Text size="B300">Deny</Text>