Add endpoint for appRatings

[nbenaglia]

Closes #329

Add Bulk App Ratings Endpoint

Summary

Adds a new API endpoint that dramatically improves performance when fetching app ratings in Qortal-Hub.

Problem

Currently, displaying app ratings requires making 2 separate API calls for each app (one for poll metadata, one for vote counts). For the community apps tab with hundreds of apps, this means 100-1000+ API calls, causing slow load times and unnecessary server load.

Solution

New endpoint GET /polls/apps/ratings returns all app rating data in a single request, reducing hundreds of API calls down to just one.

Performance Improvement:

• Featured carousel: 12 calls → 1 call
• Official apps tab: 34 calls → 1 call
• Community apps (500+): 1000+ calls → 1 call

Changes

• Added bulk ratings endpoint with filtering and pagination support
• Created optimized database query to fetch polls with vote counts
• Includes comprehensive test coverage
• Fully backward compatible with existing API

Impact

Users will experience significantly faster app browsing, especially on initial page load. The server will handle fewer concurrent requests, improving overall system performance.