feat(cli): skip interactive LLM selection when configured via environment (#873)

Setting the LLM env vars now skips the matching CLI selection step and uses
the value, so OpenAI-compatible endpoints (opencode, LM Studio, etc.) and
unattended runs work without prompting. Unset vars are chosen interactively
as before.

  TRADINGAGENTS_LLM_PROVIDER -> skips provider step (still verifies API key)
  TRADINGAGENTS_LLM_BACKEND_URL -> custom endpoint (else provider default)
  TRADINGAGENTS_DEEP_THINK_LLM / _QUICK_THINK_LLM -> skips model step
  TRADINGAGENTS_OUTPUT_LANGUAGE -> skips language step

Builds on the existing TRADINGAGENTS_* config overrides (which already feed
DEFAULT_CONFIG); this wires the CLI to honor them instead of re-prompting.

tests/test_ollama_base_url.py

@@ -7,6 +7,23 @@ import importlib
 import pytest
 
 
+@pytest.fixture(scope="module", autouse=True)
+def _resync_reloaded_modules():
+    """Restore module state after this file's importlib.reload() calls.
+
+    Several tests below reload ``cli.utils`` to re-evaluate OLLAMA_BASE_URL.
+    That leaves ``cli.main``'s star-imported names (e.g. get_ticker) bound to
+    the pre-reload module objects, which breaks identity checks in unrelated
+    tests that happen to run afterward. Re-sync once on teardown so the reload
+    doesn't leak across test modules.
+    """
+    yield
+    import cli.utils
+    import cli.main
+    importlib.reload(cli.utils)
+    importlib.reload(cli.main)
+
+
 # ---- openai_client side: _resolve_provider_base_url -----------------------