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/llm_clients/capabilities.py

@@ -18,7 +18,6 @@ import re
 from dataclasses import dataclass
 from typing import Literal
 
-
 StructuredMethod = Literal[
     "function_calling",  # uses tools; respects supports_tool_choice
     "json_mode",         # uses response_format={"type":"json_object"}