refactor: address architect review findings (6 items)

R1: Extend @safe to catch ValueError->400, simplify routes_backtest
    (eliminated 4 copies of duplicated try/except)
R2: Consolidate PROVIDER constant into obb_utils.py (single source)
R3: Add days_ago() helper to obb_utils.py, replace 8+ duplications
R4: Extract Reddit/ApeWisdom into reddit_service.py from finnhub_service
R5: Fix missing top-level import asyncio in finnhub_service
R6: (deferred - sentiment logic extraction is a larger change)

All 561 tests passing.

routes_sentiment.py

@@ -9,6 +9,7 @@ from route_utils import safe, validate_symbol
 import alphavantage_service
 import finnhub_service
 import openbb_service
+import reddit_service
 
 import logging
 
@@ -35,7 +36,7 @@ async def stock_sentiment(symbol: str = Path(..., min_length=1, max_length=20)):
     av_data, finnhub_data, reddit_data, upgrades_data, recs_data = await asyncio.gather(
         alphavantage_service.get_news_sentiment(symbol, limit=20),
         finnhub_service.get_sentiment_summary(symbol),
-        finnhub_service.get_reddit_sentiment(symbol),
+        reddit_service.get_reddit_sentiment(symbol),
         openbb_service.get_upgrades_downgrades(symbol, limit=10),
         finnhub_service.get_recommendation_trends(symbol),
         return_exceptions=True,
@@ -211,7 +212,7 @@ async def stock_reddit_sentiment(
 ):
     """Reddit sentiment: mentions, upvotes, rank on WSB/stocks/investing (free, no key)."""
     symbol = validate_symbol(symbol)
-    data = await finnhub_service.get_reddit_sentiment(symbol)
+    data = await reddit_service.get_reddit_sentiment(symbol)
     return ApiResponse(data=data)
 
 
@@ -219,5 +220,5 @@ async def stock_reddit_sentiment(
 @safe
 async def reddit_trending():
     """Top 25 trending stocks on Reddit (WSB, r/stocks, r/investing). Free, no key."""
-    data = await finnhub_service.get_reddit_trending()
+    data = await reddit_service.get_reddit_trending()
     return ApiResponse(data=data)