feat: add deals, tasks, and organizations pages with CRUD functionality

- Implemented DealsPage with deal creation, updating, and filtering features.
- Added OrganizationsPage to manage and switch between organizations.
- Created TasksPage for task management, including task creation and filtering.
- Updated router to include new pages for navigation.

frontend/src/features/deals/api.ts

@@ -0,0 +1,48 @@
+import { apiClient } from '@/lib/api-client'
+import type { Deal, DealStage, DealStatus } from '@/types/crm'
+
+export interface DealFilters {
+  page?: number
+  pageSize?: number
+  status?: DealStatus[]
+  stage?: DealStage | null
+  ownerId?: number
+  minAmount?: number | null
+  maxAmount?: number | null
+  orderBy?: 'created_at' | 'amount' | 'updated_at'
+  order?: 'asc' | 'desc'
+}
+
+export interface DealPayload {
+  contact_id: number
+  title: string
+  amount?: number | string | null
+  currency?: string | null
+  owner_id?: number | null
+}
+
+export interface DealUpdatePayload {
+  status?: DealStatus
+  stage?: DealStage
+  amount?: number | string | null
+  currency?: string | null
+}
+
+const mapFilters = (filters?: DealFilters) => ({
+  page: filters?.page,
+  page_size: filters?.pageSize,
+  status: filters?.status,
+  stage: filters?.stage ?? undefined,
+  owner_id: filters?.ownerId,
+  min_amount: filters?.minAmount ?? undefined,
+  max_amount: filters?.maxAmount ?? undefined,
+  order_by: filters?.orderBy,
+  order: filters?.order,
+})
+
+export const listDeals = (filters?: DealFilters) => apiClient.get<Deal[]>('/deals/', { params: mapFilters(filters) })
+
+export const createDeal = (payload: DealPayload) => apiClient.post<Deal, DealPayload>('/deals/', payload)
+
+export const updateDeal = (dealId: number, payload: DealUpdatePayload) =>
+  apiClient.patch<Deal, DealUpdatePayload>(`/deals/${dealId}`, payload)