Spun off from #62 as the "phase 2" provider track, kept separate from the fundamental data layer so each stays reviewable.

The fundamental data layer (#74 / #76) now covers financial statements + indicators for pre-filtering. A separate track is news / announcement / sentiment / event factors — e.g. RSSHub as an entry point — for strategies that key off catalysts and sentiment rather than fundamentals alone.

Scope to discuss:

• RSSHub (or similar) as a source for news / filings / sentiment feeds
• a sentiment / event provider contract, parallel to the fundamental provider
• mapping feeds to symbols + timestamps with point-in-time correctness (no look-ahead)
• a representative event/sentiment-driven pre-filter or signal example

Context: raised by @shadowinlife in #62 (RSSHub-driven sentiment factors).