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-settings/RoomServerACL.tsx

@@ -33,6 +33,7 @@ import { SequenceCard } from '../../components/sequence-card';
 import { SequenceCardStyle } from '../common-settings/styles.css';
 import { stopPropagation } from '../../utils/keyboard';
 import { isValidServerPattern, matchesAnyGlob } from '../../utils/serverAcl';
+import { MobileTouchTarget } from '../../styles/mobile.css';
 import { useModalStyle } from '../../hooks/useModalStyle';
 
 // ── Types ─────────────────────────────────────────────────────────────────────
@@ -148,6 +149,7 @@ function ServerList({ label, entries, canEdit, onAdd, onRemove }: ServerListProp
                   size="300"
                   variant="Background"
                   radii="300"
+                  className={MobileTouchTarget}
                   aria-label={`Remove ${entry}`}
                   onClick={() => onRemove(i)}
                   style={{ flexShrink: 0 }}