Add paste-your-songs manual import feature

Users can now paste a list of songs as text to create a playlist without
needing any service integration. Supports multiple formats: "Artist - Title",
"Title by Artist", "Artist: Title", and numbered lists. Includes a live
song count preview in the modal and free tier playlist limit enforcement.

frontend/src/lib/api.ts

@@ -171,6 +171,30 @@ export const importYouTubePlaylist = (url: string) =>
 export const searchYouTubeMusic = (query: string) =>
   api.post<YouTubeTrackResult[]>('/youtube-music/search', { query }).then((r) => r.data)
 
+// Last.fm Import
+export interface LastfmPreviewTrack {
+  title: string
+  artist: string
+  playcount: number
+  image_url: string | null
+}
+
+export interface LastfmPreviewResponse {
+  display_name: string
+  track_count: number
+  sample_tracks: LastfmPreviewTrack[]
+}
+
+export const previewLastfm = (username: string) =>
+  api.get<LastfmPreviewResponse>('/lastfm/preview', { params: { username } }).then((r) => r.data)
+
+export const importLastfm = (username: string, period: string) =>
+  api.post<PlaylistDetailResponse>('/lastfm/import', { username, period }).then((r) => r.data)
+
+// Manual Import (paste songs)
+export const importPastedSongs = (name: string, text: string) =>
+  api.post<PlaylistDetailResponse>('/import/paste', { name, text }).then((r) => r.data)
+
 // Billing
 export interface BillingStatusResponse {
   is_pro: boolean