feat: Binance WS, news client, and social client

Add ThreadedWebsocketManager-based BinanceWSClient for real-time price
streaming, NewsClient for CryptoPanic/NewsAPI fetching with coin filtering,
and SocialClient for Reddit post retrieval with keyword filtering and
simple keyword-based sentiment scoring. Includes unit tests for news and
social clients (4/4 passing).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_social_client.py

@@ -0,0 +1,25 @@
+import pytest
+from data.social_client import SocialClient
+
+def test_analyze_reddit_posts():
+    client = SocialClient(reddit_client_id="x", reddit_secret="x", reddit_user_agent="x")
+    posts = [
+        {"title": "Bitcoin is amazing! Going to the moon!", "score": 100, "num_comments": 50},
+        {"title": "BTC crash incoming, sell everything now", "score": 20, "num_comments": 10},
+        {"title": "Bitcoin steady at 40k, not bad", "score": 50, "num_comments": 30},
+    ]
+    result = client.simple_sentiment(posts)
+    assert "positive" in result
+    assert "negative" in result
+    assert "neutral" in result
+    assert result["positive"] + result["negative"] + result["neutral"] == len(posts)
+
+def test_keyword_match():
+    client = SocialClient(reddit_client_id="x", reddit_secret="x", reddit_user_agent="x")
+    posts = [
+        {"title": "Bitcoin BTC going up"},
+        {"title": "Ethereum news today"},
+        {"title": "BTC and ETH analysis"},
+    ]
+    filtered = client.filter_posts_by_coin(posts, "BTC")
+    assert len(filtered) == 2