Refactor API structure and integrate new modular API client

- Replaced legacy apiService with a new modular api client structure.
- Updated AuthContext, OAuthButtons, and AuthCallbackPage to use the new api client.
- Created separate services for auth, sounds, playlists, and users.
- Implemented centralized API configuration and error handling.
- Added support for OAuth providers and token exchange.
- Introduced a Toaster component for notifications in App.
- Updated API endpoints and request handling for better maintainability.

src/lib/api/services/playlists.ts

@@ -0,0 +1,94 @@
+import { apiClient } from '../client'
+import { API_CONFIG } from '../config'
+import type { PaginatedResponse } from '../types'
+import type { Sound } from './sounds'
+
+export interface Playlist {
+  id: number
+  name: string
+  description?: string
+  user_id: number
+  is_public: boolean
+  sounds: Sound[]
+  created_at: string
+  updated_at: string
+}
+
+export interface CreatePlaylistRequest {
+  name: string
+  description?: string
+  is_public?: boolean
+}
+
+export interface UpdatePlaylistRequest {
+  name?: string
+  description?: string
+  is_public?: boolean
+}
+
+export interface PlaylistsListParams {
+  page?: number
+  size?: number
+  search?: string
+  user_id?: number
+  is_public?: boolean
+}
+
+export interface AddSoundToPlaylistRequest {
+  sound_id: number
+}
+
+export class PlaylistsService {
+  /**
+   * Get list of playlists with pagination
+   */
+  async list(params?: PlaylistsListParams): Promise<PaginatedResponse<Playlist>> {
+    return apiClient.get<PaginatedResponse<Playlist>>(API_CONFIG.ENDPOINTS.PLAYLISTS.LIST, { 
+      params: params as Record<string, string | number | boolean | undefined>
+    })
+  }
+
+  /**
+   * Get a specific playlist by ID
+   */
+  async get(id: string | number): Promise<Playlist> {
+    return apiClient.get<Playlist>(API_CONFIG.ENDPOINTS.PLAYLISTS.GET(id))
+  }
+
+  /**
+   * Create a new playlist
+   */
+  async create(data: CreatePlaylistRequest): Promise<Playlist> {
+    return apiClient.post<Playlist>(API_CONFIG.ENDPOINTS.PLAYLISTS.CREATE, data)
+  }
+
+  /**
+   * Update an existing playlist
+   */
+  async update(id: string | number, data: UpdatePlaylistRequest): Promise<Playlist> {
+    return apiClient.patch<Playlist>(API_CONFIG.ENDPOINTS.PLAYLISTS.UPDATE(id), data)
+  }
+
+  /**
+   * Delete a playlist
+   */
+  async delete(id: string | number): Promise<void> {
+    return apiClient.delete<void>(API_CONFIG.ENDPOINTS.PLAYLISTS.DELETE(id))
+  }
+
+  /**
+   * Add a sound to a playlist
+   */
+  async addSound(playlistId: string | number, data: AddSoundToPlaylistRequest): Promise<Playlist> {
+    return apiClient.post<Playlist>(`${API_CONFIG.ENDPOINTS.PLAYLISTS.GET(playlistId)}/sounds`, data)
+  }
+
+  /**
+   * Remove a sound from a playlist
+   */
+  async removeSound(playlistId: string | number, soundId: string | number): Promise<Playlist> {
+    return apiClient.delete<Playlist>(`${API_CONFIG.ENDPOINTS.PLAYLISTS.GET(playlistId)}/sounds/${soundId}`)
+  }
+}
+
+export const playlistsService = new PlaylistsService()