feat: P1 features — quick switcher, media gallery, DM previews, knock-to-join, syntax highlighting

P1-1: Quick room switcher (Ctrl+K/Cmd+K) — QuickSwitcher.tsx + ClientNonUIFeatures hotkey
P1-2: Media gallery drawer (images/videos/files) — MediaGallery.tsx + RoomViewHeader toggle
P1-4: DM last message preview + relative timestamp in RoomNavItem when direct=true
P1-7: Code syntax highlighting — TDS tokenizer (syntaxHighlight.ts), custom CSS theme
       (.prism-tds-dark/.prism-tds-light), applied in react-custom-html-parser.tsx
P1-11: Knock-to-join — "Request to Join" in RoomIntro + Pending Requests in MembersDrawer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/components/room-intro/RoomIntro.tsx

@@ -10,8 +10,9 @@ import {
   Spinner,
   Text,
   as,
+  color,
 } from 'folds';
-import { Room } from 'matrix-js-sdk';
+import { JoinRule, Room } from 'matrix-js-sdk';
 import { useAtomValue } from 'jotai';
 import { IRoomCreateContent, Membership, StateEvent } from '../../../types/matrix/room';
 import { getMemberDisplayName, getStateEvent } from '../../utils/room';
@@ -42,6 +43,8 @@ export const RoomIntro = as<'div', RoomIntroProps>(({ room, ...props }, ref) =>
   const mDirects = useAtomValue(mDirectAtom);
   const [invitePrompt, setInvitePrompt] = useState(false);
   const [viewTopic, setViewTopic] = useState(false);
+  const [knocked, setKnocked] = useState(false);
+  const [knockError, setKnockError] = useState<string | undefined>();
 
   const createEvent = getStateEvent(room, StateEvent.RoomCreate);
   const avatarMxc = useRoomAvatar(room, mDirects.has(room.roomId));
@@ -168,6 +171,36 @@ export const RoomIntro = as<'div', RoomIntroProps>(({ room, ...props }, ref) =>
                 <Text size="B300">Join Old Room</Text>
               </Button>
             ))}
+          {room.getJoinRule() === JoinRule.Knock &&
+            room.getMyMembership() !== Membership.Join &&
+            (knocked ? (
+              <Text size="T300" priority="300">
+                Request sent — waiting for room admin approval
+              </Text>
+            ) : (
+              <>
+                <Button
+                  onClick={() => {
+                    setKnockError(undefined);
+                    mx.knockRoom(room.roomId)
+                      .then(() => setKnocked(true))
+                      .catch((err: Error) =>
+                        setKnockError(err.message ?? 'Failed to send request'),
+                      );
+                  }}
+                  variant="Primary"
+                  size="300"
+                  radii="300"
+                >
+                  <Text size="B300">Request to Join</Text>
+                </Button>
+                {knockError && (
+                  <Text size="T300" style={{ color: color.Critical.Main }}>
+                    {knockError}
+                  </Text>
+                )}
+              </>
+            ))}
         </Box>
       </Box>
     </Box>