🔧 Standardize TanStack Query Implementation

[zalexa19]

Standardize the TanStack Query setup across the client by properly organizing queries, mutations, types, and query key factories according to best practices.
🎯 Goals

• Separate queries from mutations into dedicated files
• Create proper TypeScript interfaces for all API requests/responses
• Implement query key factories for all features
• Ensure consistent file structure across all features

📝 Implementation Guidelines
Each feature's data/ folder should follow this structure:

feature/
└── data/
    ├── types.ts           # Request/Response types
    ├── queries.ts         # GET operations with hooks
    ├── mutations.ts       # POST/PUT/PATCH/DELETE with hooks
    └── queryKeys.ts       # Query key factory

Query Key Factory Pattern
Reference the existing pattern in search/data/queries.ts
Types File Structure

// types.ts
export interface FeatureRequest {
  // Request payload fields
}

export interface FeatureResponse {
  // Response data fields
}

export interface FeatureListResponse {
  // Array or paginated response
}

Definition of done:

• All features have separated queries.ts and mutations.ts files
• All features have types.ts with proper Request/Response interfaces
• All features have queryKeys.ts with key factories
• All query hooks use the key factory functions
• All mutations properly invalidate queries using key factories
• No mixed query/mutation files remain
• All //fixme: comments related to types are resolved
• Documentation updated in CLIENT_STRUCTURE.md if needed