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.

cli/utils.py

@@ -1,6 +1,5 @@
 import os
 from pathlib import Path
-from typing import List, Optional, Tuple, Dict
 
 import questionary
 from dotenv import find_dotenv, set_key
@@ -89,8 +88,8 @@ def detect_asset_type(ticker: str) -> AssetType:
 
 
 def filter_analysts_for_asset_type(
-    analysts: List[AnalystType], asset_type: AssetType
-) -> List[AnalystType]:
+    analysts: list[AnalystType], asset_type: AssetType
+) -> list[AnalystType]:
     if asset_type != AssetType.CRYPTO:
         return analysts
     return [
@@ -133,7 +132,7 @@ def get_analysis_date() -> str:
     return date.strip()
 
 
-def select_analysts(asset_type: AssetType = AssetType.STOCK) -> List[AnalystType]:
+def select_analysts(asset_type: AssetType = AssetType.STOCK) -> list[AnalystType]:
     """Select analysts using an interactive checkbox."""
     available_analysts = filter_analysts_for_asset_type(
         [value for _, value in ANALYST_ORDER],
@@ -197,7 +196,7 @@ def select_research_depth() -> int:
     return choice
 
 
-def _fetch_openrouter_models() -> List[Tuple[str, str]]:
+def _fetch_openrouter_models() -> list[tuple[str, str]]:
     """Fetch available models from the OpenRouter API."""
     import requests
     try:
@@ -377,7 +376,7 @@ def select_llm_provider() -> tuple[str, str | None]:
             ]
         ),
     ).ask()
-    
+
     if choice is None:
         console.print("\n[red]No LLM provider selected. Exiting...[/red]")
         exit(1)
@@ -556,7 +555,7 @@ def confirm_ollama_endpoint(url: str) -> None:
         )
 
 
-def ensure_api_key(provider: str) -> Optional[str]:
+def ensure_api_key(provider: str) -> str | None:
     """Make sure the API key for `provider` is available in the environment.
 
     If the env var is already set, returns its value untouched. Otherwise