refactor: align display label and docs with sentiment_analyst rename

The agent ingests news, StockTwits, and Reddit, but CLI labels, the
README description, and the legacy shim docstring still framed it as
social-media-only. Updates all user-visible surfaces so the name and
the implementation match.

tradingagents/agents/analysts/social_media_analyst.py

@@ -1,9 +1,9 @@
-"""Backwards-compatibility shim for the renamed social_media_analyst module.
+"""Backwards-compatibility shim for the renamed module.
 
-The social media analyst has been renamed to ``sentiment_analyst`` because its
-only data tool is ``get_news`` (Yahoo Finance), not a social media feed.
-
-Import from ``tradingagents.agents.analysts.sentiment_analyst`` going forward.
+The agent is now ``sentiment_analyst`` and aggregates Yahoo Finance news,
+StockTwits cashtag streams, and Reddit posts into a single sentiment
+report. Import from ``tradingagents.agents.analysts.sentiment_analyst``
+going forward; this module will be removed in a future release.
 
 See: https://github.com/TauricResearch/TradingAgents/issues/557
 """