feat: add PostgreSQL database support and development scripts

- Added pg and @types/pg dependencies for PostgreSQL integration
- Created database testing and backend initialization scripts
- Changed dev server port to 3002 to avoid conflicts

src/models/Package.ts

@@ -0,0 +1,86 @@
+export interface Package {
+  id: string
+  name: string
+  description?: string
+  version?: string
+  platform_id: string
+  category_id?: number
+  license_id?: number
+  type?: 'gui' | 'cli'
+  repository?: 'official' | 'third-party'
+  homepage_url?: string
+  download_url?: string
+  last_updated?: Date
+  downloads_count?: number
+  popularity_score?: number
+  is_active: boolean
+  created_at: Date
+  updated_at: Date
+  
+  // Joined fields
+  platform?: Platform
+  category?: Category
+  license?: License
+  tags?: string[]
+  dependencies?: Package[]
+}
+
+export interface Platform {
+  id: string
+  name: string
+  package_manager: string
+  icon?: string
+}
+
+export interface Category {
+  id: number
+  name: string
+  description?: string
+}
+
+export interface License {
+  id: number
+  name: string
+  url?: string
+}
+
+export interface CreatePackageInput {
+  id: string
+  name: string
+  description?: string
+  version?: string
+  platform_id: string
+  category_id?: number
+  license_id?: number
+  type?: 'gui' | 'cli'
+  repository?: 'official' | 'third-party'
+  homepage_url?: string
+  download_url?: string
+  popularity_score?: number
+}
+
+export interface UpdatePackageInput {
+  name?: string
+  description?: string
+  version?: string
+  category_id?: number
+  license_id?: number
+  type?: 'gui' | 'cli'
+  repository?: 'official' | 'third-party'
+  homepage_url?: string
+  download_url?: string
+  popularity_score?: number
+  is_active?: boolean
+}
+
+export interface PackageFilter {
+  platform_id?: string
+  category_id?: number
+  type?: 'gui' | 'cli'
+  repository?: 'official' | 'third-party'
+  search?: string
+  limit?: number
+  offset?: number
+  sort_by?: 'name' | 'popularity_score' | 'last_updated' | 'downloads_count'
+  sort_order?: 'asc' | 'desc'
+}

src/models/Platform.ts

@@ -0,0 +1,21 @@
+export interface Platform {
+  id: string
+  name: string
+  package_manager: string
+  icon?: string
+  created_at: Date
+  updated_at: Date
+}
+
+export interface CreatePlatformInput {
+  id: string
+  name: string
+  package_manager: string
+  icon?: string
+}
+
+export interface UpdatePlatformInput {
+  name?: string
+  package_manager?: string
+  icon?: string
+}