Fix analytics tests and add comprehensive testing guide

Critical Fixes:
- Fixed Price model query to use security_id join with Security
- Added Security import to returns.py module
- Fixed all test fixtures to use test_db_session correctly
- Added AAPL price data to sample_prices fixture

New Tests:
- tests/test_analytics_integration.py: 10 comprehensive integration tests
  * Real-world scenarios with synthetic price data
  * Return calculations, benchmark comparisons, performance metrics
  * Edge cases: missing data, sell trades, disclosure timing

Documentation:
- LOCAL_TEST_GUIDE.md: Complete guide for local testing
  * How to test before deploying
  * Current data status (live vs fixtures)
  * Multiple options for getting real data
  * Common issues and fixes

Test Results:
✅ All 55 tests passing
✅ Analytics fully functional
✅ Ready for deployment

Live Data Status:
❌ House Stock Watcher API still down (external issue)
✅ Manual CSV import works
✅ yfinance for prices works
✅ Can use system NOW with manual data

src/pote/analytics/returns.py

@@ -11,7 +11,7 @@ import pandas as pd
 from sqlalchemy import select
 from sqlalchemy.orm import Session
 
-from pote.db.models import Price, Trade
+from pote.db.models import Price, Security, Trade
 
 logger = logging.getLogger(__name__)
 
@@ -166,11 +166,12 @@ class ReturnCalculator:
         start_date = target_date - timedelta(days=days_tolerance)
         end_date = target_date + timedelta(days=days_tolerance)
 
-        # Query prices near target date
+        # Query prices near target date (join with Security to filter by ticker)
         prices = (
             self.session.query(Price)
+            .join(Security)
             .filter(
-                Price.ticker == ticker,
+                Security.ticker == ticker,
                 Price.date >= start_date,
                 Price.date <= end_date,
             )
@@ -209,8 +210,9 @@ class ReturnCalculator:
         """
         prices = (
             self.session.query(Price)
+            .join(Security)
             .filter(
-                Price.ticker == ticker,
+                Security.ticker == ticker,
                 Price.date >= start_date,
                 Price.date <= end_date,
             )