feat(sentiment): screen social posts with TypeSafe's Jev (#1376)

- with TYPESAFE_API_KEY set, each StockTwits and Reddit post is asked whether it is about the company and its stance on the stock
- posts clearly about something else are dropped before the per-source cut, and each block opens with a stance count
- any failed request leaves the source's posts unscreened and says so; without a key nothing changes

tests/test_stocktwits_resilience.py

@@ -8,6 +8,7 @@ transport error must degrade to a placeholder rather than raise.
 from __future__ import annotations
 
 import http.client
+import json
 from unittest.mock import patch
 from urllib.error import HTTPError
 
@@ -75,3 +76,41 @@ class TestStockTwitsCryptoSymbols:
         with patch.object(stocktwits, "urlopen", side_effect=fake_urlopen):
             stocktwits.fetch_stocktwits_messages("BTC-USD")
         assert "/symbol/BTC.X.json" in seen["url"]
+
+
+def _stream(*bodies):
+    payload = {"messages": [
+        {"body": b, "created_at": "2026-01-09T15:00:00Z", "user": {"username": "u"},
+         "entities": {"sentiment": {"basic": "Bullish"}}}
+        for b in bodies
+    ]}
+
+    class _Resp:
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *a):
+            return False
+
+        def read(self):
+            return json.dumps(payload).encode()
+    return _Resp()
+
+
+def _drop_spam(texts):
+    return [not t.startswith("SPAM") for t in texts], "Screened: note"
+
+
+@pytest.mark.unit
+class TestStockTwitsScreening:
+    def test_screened_out_messages_leave_the_block_and_its_counts(self):
+        with patch.object(stocktwits, "urlopen", return_value=_stream("SPAM", "long NVDA")):
+            out = stocktwits.fetch_stocktwits_messages("NVDA", screen=_drop_spam)
+        assert out.startswith("Screened: note")
+        assert "long NVDA" in out and "SPAM" not in out
+        assert "Total: 1 most-recent" in out
+
+    def test_all_screened_out_is_not_called_empty(self):
+        with patch.object(stocktwits, "urlopen", return_value=_stream("SPAM")):
+            out = stocktwits.fetch_stocktwits_messages("NVDA", screen=_drop_spam)
+        assert "none of the 1 StockTwits messages is about $NVDA" in out