#355 Remove hardcoded mock data from http_request.py

## Issue http_request.py lines 146-178 contain hardcoded mock data for offline testing. ## Current Behavior If URL contains api.publicapis.org/entries and title=cat, returns hardcoded response without making actual HTTP request. ## Risk - Confusing behavior in production - Tests may pass incorrectly ## Required Fix 1. Remove mock data OR 2. Move to separate test_http_request.py mock 3. Add HIGHWAY_HTTP_MOCK_MODE env var to enable mocking ## Location engine/tools/http_request.py:146-178