chore(lint): make the repository ruff-clean under the strict select

Clear the deferred full-repo lint backlog so the whole tree passes the strict
ruff select (E,W,F,I,B,UP,C4,SIM). Mechanical fixes dominate: import sorting,
pep585/604 annotations, dropped dead imports, and whitespace. The few semantic
changes are behavior-preserving: declare __all__ on the agent_utils and
alpha_vantage re-export hubs; expand 'from x import *' to explicit names; use
immutable tuple defaults instead of mutable list defaults; contextlib.suppress
for try/except/pass; and narrow an over-broad assertRaises.

tradingagents/graph/propagation.py

@@ -1,8 +1,8 @@
 # TradingAgents/graph/propagation.py
 
-from typing import Dict, Any, List, Optional
+from typing import Any
+
 from tradingagents.agents.utils.agent_states import (
-    AgentState,
     InvestDebateState,
     RiskDebateState,
 )
@@ -22,7 +22,7 @@ class Propagator:
         asset_type: str = "stock",
         past_context: str = "",
         instrument_context: str = "",
-    ) -> Dict[str, Any]:
+    ) -> dict[str, Any]:
         """Create the initial state for the agent graph.
 
         ``instrument_context`` is the deterministic ticker-identity string
@@ -68,7 +68,7 @@ class Propagator:
             "news_report": "",
         }
 
-    def get_graph_args(self, callbacks: Optional[List] = None) -> Dict[str, Any]:
+    def get_graph_args(self, callbacks: list | None = None) -> dict[str, Any]:
         """Get arguments for the graph invocation.
 
         Args: