feat(web): add duplicate playlist flow under the New nav button

Adds a "Duplicate Playlist" secondary action to the sidebar's New (+)
popup menu. Opens a modal where the user pastes any public Audius
playlist URL, sees a preview of the source playlist (title, description,
cover art), and toggles per-field switches to customize what should
differ in the copy. The duplicated playlist is created as private by
default (enforced by the existing optimisticallySavePlaylist saga).

Scope:
- Metadata-only duplication for now. Tracks are not copied — a follow-up
  PR will support full duplicate including track contents. The modal
  surfaces this with a helper line so users know they need to add tracks
  separately.
- Reuses the existing createPlaylist saga: when artwork is not
  customized, we pass the source playlist's cover_art_sizes CID through
  so the saga reuses the cover instead of treating it as a new upload.

Implementation:
- New `DuplicatePlaylistModal` Redux modal slice (createModal helper).
- New `DuplicatePlaylistModal` component (Harmony Modal + TextInput +
  Switch + TextArea + Artwork + UploadArtwork).
- Resolves pasted URL → permalink via `getPathFromPlaylistUrl`, then
  loads the source via `useCollectionByPermalink`.
- Wires "Duplicate Playlist" into `CreatePlaylistLibraryItemButton`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dylanjeffers

packages/common/src/store/ui/modals/duplicate-playlist-modal/index.ts

@@ -0,0 +1,20 @@
+import { createModal } from '../createModal'
+
+export type DuplicatePlaylistModalState = {
+  isAlbum?: boolean
+}
+
+const duplicatePlaylistModal = createModal<DuplicatePlaylistModalState>({
+  reducerPath: 'DuplicatePlaylistModal',
+  initialState: {
+    isOpen: false,
+    isAlbum: false
+  },
+  sliceSelector: (state) => state.ui.modals
+})
+
+export const {
+  hook: useDuplicatePlaylistModal,
+  reducer: duplicatePlaylistModalReducer,
+  actions: duplicatePlaylistModalActions
+} = duplicatePlaylistModal

packages/common/src/store/ui/modals/index.ts

@@ -42,3 +42,4 @@ export * from './send-tokens-modal'
 export * from './coin-success-modal'
 export * from './fan-club-details-modal'
 export * from './create-playlist-modal'
+export * from './duplicate-playlist-modal'

packages/common/src/store/ui/modals/parentSlice.ts

@@ -84,7 +84,8 @@ export const initialState: BasicModalsState = {
   FanClubDetailsModal: { isOpen: false },
   VerificationSuccess: { isOpen: false },
   VerificationError: { isOpen: false },
-  CreatePlaylistModal: { isOpen: false }
+  CreatePlaylistModal: { isOpen: false },
+  DuplicatePlaylistModal: { isOpen: false }
 }
 
 const slice = createSlice({

packages/common/src/store/ui/modals/reducers.ts

@@ -15,6 +15,7 @@ import { createChatModalReducer } from './create-chat-modal'
 import { createPlaylistModalReducer } from './create-playlist-modal'
 import { deleteTrackConfirmationModalReducer } from './delete-track-confirmation-modal'
 import { downloadTrackArchiveModalReducer } from './download-track-archive-modal'
+import { duplicatePlaylistModalReducer } from './duplicate-playlist-modal'
 import { earlyReleaseConfirmationModalReducer } from './early-release-confirmation-modal'
 import { editAccessConfirmationModalReducer } from './edit-access-confirmation-modal'
 import { externalWalletSignUpModalReducer } from './external-wallet-sign-up-modal'
@@ -94,7 +95,8 @@ const combinedReducers = combineReducers({
   SendTokensModal: sendTokensModalReducer,
   CoinSuccessModal: coinSuccessModalReducer,
   FanClubDetailsModal: fanClubDetailsModalReducer,
-  CreatePlaylistModal: createPlaylistModalReducer
+  CreatePlaylistModal: createPlaylistModalReducer,
+  DuplicatePlaylistModal: duplicatePlaylistModalReducer
 })
 
 /**

packages/common/src/store/ui/modals/types.ts

@@ -120,6 +120,7 @@ export type Modals =
   | 'VerificationSuccess'
   | 'VerificationError'
   | 'CreatePlaylistModal'
+  | 'DuplicatePlaylistModal'
 
 export type BasicModalsState = {
   [modal in Modals]: BaseModalState