test: improve test coverage from 61% to 84.81%

Major improvements:
- Fixed all 42 broken tests (database connection leaks)
- Added db_connection() context manager for proper cleanup
- Created comprehensive test suites for undertested modules

New test coverage:
- tools/general_tools.py: 26 tests (97% coverage)
- tools/price_tools.py: 11 tests (validates NASDAQ symbols, date handling)
- api/price_data_manager.py: 12 tests (85% coverage)
- api/routes/results_v2.py: 3 tests (98% coverage)
- agent/reasoning_summarizer.py: 2 tests (87% coverage)
- api/routes/period_metrics.py: 2 edge case tests (100% coverage)
- agent/mock_provider: 1 test (100% coverage)

Database fixes:
- Added db_connection() context manager to prevent leaks
- Updated 16+ test files to use context managers
- Fixed drop_all_tables() to match new schema
- Added CHECK constraint for action_type
- Added ON DELETE CASCADE to trading_days foreign key

Test improvements:
- Updated SQL INSERT statements with all required fields
- Fixed date parameter handling in API integration tests
- Added edge case tests for validation functions
- Fixed import errors across test suite

Results:
- Total coverage: 84.81% (was 61%)
- Tests passing: 406 (was 364 with 42 failures)
- Total lines covered: 6364 of 7504

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

tests/unit/test_reasoning_summarizer.py

@@ -78,3 +78,48 @@ class TestReasoningSummarizer:
         summary = await summarizer.generate_summary([])
 
         assert summary == "No trading activity recorded."
+
+    @pytest.mark.asyncio
+    async def test_format_reasoning_with_trades(self):
+        """Test formatting reasoning log with trade executions."""
+        mock_model = AsyncMock()
+        summarizer = ReasoningSummarizer(model=mock_model)
+
+        reasoning_log = [
+            {"role": "assistant", "content": "Analyzing market conditions"},
+            {"role": "tool", "name": "buy", "content": "Bought 10 AAPL shares"},
+            {"role": "tool", "name": "sell", "content": "Sold 5 MSFT shares"},
+            {"role": "assistant", "content": "Trade complete"}
+        ]
+
+        formatted = summarizer._format_reasoning_for_summary(reasoning_log)
+
+        # Should highlight trades at the top
+        assert "TRADES EXECUTED" in formatted
+        assert "BUY" in formatted
+        assert "SELL" in formatted
+        assert "AAPL" in formatted
+        assert "MSFT" in formatted
+
+    @pytest.mark.asyncio
+    async def test_generate_summary_with_non_string_response(self):
+        """Test handling AI response that doesn't have content attribute."""
+        # Mock AI model that returns a non-standard object
+        mock_model = AsyncMock()
+
+        # Create a custom object without 'content' attribute
+        class CustomResponse:
+            def __str__(self):
+                return "Summary via str()"
+
+        mock_model.ainvoke.return_value = CustomResponse()
+
+        summarizer = ReasoningSummarizer(model=mock_model)
+
+        reasoning_log = [
+            {"role": "assistant", "content": "Trading activity"}
+        ]
+
+        summary = await summarizer.generate_summary(reasoning_log)
+
+        assert summary == "Summary via str()"