feat: multi-region parallel search for top stories

feat: 100% live search-only top stories with multi-query parallelization

fix: guarantee 6 top stories with 30-day fallback and regional expansion

feat: guarantee 6 top stories with vector DB fallback

feat: refine search query and increase top stories limit to 6

fix: resolve Depends NameError and ensure logging integrity

feat: visual top stories, redis caching, and automated 4-hour refresh

fix(rag-api): add msgpack and confluent-kafka to requirements, safe import

feat(rag-api): hybrid top stories — 3 from Kafka news.processed + 3 from DuckDuckGo

feat: add top stories API + fix reranker tokenizer