fix: load scanners in __init__ to survive linter auto-fix

Final fix for scanner registration issue. Previous attempts
to add scanner import at module level were removed by the
pre-commit hook's ruff --fix auto-formatter.

Solution:
- Import scanners inside DiscoveryGraph.__init__() method
- Use the import (assign to _) so it's not "unused"
- Linter won't remove imports that are actually used

This ensures scanners always load when DiscoveryGraph is instantiated.

Verified: 8 scanners now properly registered

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

tradingagents/graph/discovery_graph.py

@@ -3,7 +3,6 @@ from typing import Any, Callable, Dict, List, Optional
 from langgraph.graph import END, StateGraph
 
 from tradingagents.agents.utils.agent_states import DiscoveryState
-from tradingagents.dataflows.discovery import scanners  # noqa: F401  # Load scanners to trigger registration
 from tradingagents.dataflows.discovery.scanner_registry import SCANNER_REGISTRY
 from tradingagents.dataflows.discovery.utils import PRIORITY_ORDER, Priority, serialize_for_log
 from tradingagents.tools.executor import execute_tool
@@ -66,6 +65,10 @@ class DiscoveryGraph:
         """
         self.config = config or {}
 
+        # Load scanner modules to trigger registration
+        from tradingagents.dataflows.discovery import scanners
+        _ = scanners  # Ensure scanners module is loaded
+
         # Initialize LLMs
         from tradingagents.utils.llm_factory import create_llms