🎨(frontend) clarify type-only JS imports for better code splitting

Mark JS imports as type-only when applicable so they are stripped at
build time and ignored during chunk splitting, ensuring we take full
advantage of Rollup's code-splitting optimizations.

src/frontend/src/features/rooms/components/Conference.tsx

@@ -9,7 +9,7 @@ import {
   DisconnectReason,
   MediaDeviceFailure,
   Room,
-  RoomOptions,
+  type RoomOptions,
   VideoPresets,
 } from 'livekit-client'
 import { keys } from '@/api/queryKeys'
@@ -18,7 +18,7 @@ import { Screen } from '@/layout/Screen'
 import { QueryAware } from '@/components/QueryAware'
 import { ErrorScreen } from '@/components/ErrorScreen'
 import { fetchRoom } from '../api/fetchRoom'
-import { ApiRoom } from '../api/ApiRoom'
+import type { ApiRoom } from '../api/ApiRoom'
 import { useCreateRoom } from '../api/createRoom'
 import { InviteDialog } from './InviteDialog'
 import { VideoConference } from '../livekit/prefabs/VideoConference'

src/frontend/src/features/rooms/components/Join.tsx

@@ -6,8 +6,8 @@ import { useEffect, useMemo, useRef, useState } from 'react'
 import {
   createLocalAudioTrack,
   createLocalVideoTrack,
-  LocalAudioTrack,
-  LocalVideoTrack,
+  type LocalAudioTrack,
+  type LocalVideoTrack,
   Track,
 } from 'livekit-client'
 import { H } from '@/primitives/H'
@@ -30,7 +30,7 @@ import { keys } from '@/api/queryKeys'
 import { useLobby } from '../hooks/useLobby'
 import { useQuery } from '@tanstack/react-query'
 import { queryClient } from '@/api/queryClient'
-import { ApiLobbyStatus, ApiRequestEntry } from '../api/requestEntry'
+import { ApiLobbyStatus, type ApiRequestEntry } from '../api/requestEntry'
 import { Spinner } from '@/primitives/Spinner'
 import { ApiAccessLevel } from '../api/ApiRoom'
 import { useLoginHint } from '@/hooks/useLoginHint'

src/frontend/src/features/rooms/components/MediaDeviceErrorAlert.tsx

@@ -1,4 +1,4 @@
-import { MediaDeviceFailure } from 'livekit-client'
+import type { MediaDeviceFailure } from 'livekit-client'
 import { useTranslation } from 'react-i18next'
 import { Button, Dialog, P } from '@/primitives'
 

src/frontend/src/features/rooms/components/Rating.tsx

@@ -7,7 +7,7 @@ import { usePostHog } from 'posthog-js/react'
 import type { PostHog } from 'posthog-js'
 import { Button as RACButton } from 'react-aria-components'
 import { useIsAnalyticsEnabled } from '@/features/analytics/hooks/useIsAnalyticsEnabled'
-import { CandidateInfo } from '@/stores/connectionObserver'
+import type { CandidateInfo } from '@/stores/connectionObserver'
 
 const Card = styled('div', {
   base: {