feat(cli): run an analysis without questions from flags (#1127, #1133)

- --ticker, --date and --analysts answer their steps, checked as the prompts check them; --save/--no-save and --show/--no-show answer the questions after the run
- with no terminal, the run stops before it starts and names every flag or TRADINGAGENTS_* variable still needed; a missing API key and an announcement no longer wait for input
- README shows an unattended run

tests/test_cli_commands.py

@@ -25,7 +25,8 @@ calls: list = []
 @pytest.mark.unit
 def test_no_arguments_still_runs_an_analysis(runner):
     assert runner.invoke(m.app, []).exit_code == 0
-    assert calls == [("analysis", {"checkpoint": None, "portfolio": None})]
+    no_flags = {"ticker": None, "date": None, "analysts": None, "save": None, "show": None}
+    assert calls == [("analysis", {"checkpoint": None, "portfolio": None, "flags": no_flags})]
 
 
 @pytest.mark.unit