Refactor CLI and LLM runtime handling for improved user experience

- Removed deprecated console usage in favor of structured logging functions for error handling and user prompts.
- Enhanced CLI prompts for LLM runtime and preset selection, utilizing menu helpers for better user interaction.
- Updated GPU pool scanning output with improved formatting and error indication for clarity.
- Refactored setup wizard to streamline LLM runtime and preset configuration, ensuring a more intuitive setup process.
- Improved documentation and user feedback in CLI outputs to enhance overall usability.

tests/test_prompts.py

@@ -0,0 +1,32 @@
+from gpu_rent.prompts import MenuItem, prompt_menu, resolve_menu_choice
+
+
+def test_resolve_by_number():
+    items = [MenuItem("a", "A"), MenuItem("b", "B"), MenuItem("keep", "K")]
+    assert resolve_menu_choice("2", items, default_key="keep") == "b"
+    assert resolve_menu_choice("", items, default_key="keep") == "keep"
+    assert resolve_menu_choice("keep", items, default_key="a") == "keep"
+
+
+def test_prompt_menu_prints_and_picks():
+    items = [
+        MenuItem("recommended", "rec"),
+        MenuItem("light", "lit"),
+        MenuItem("keep", "keep yaml"),
+    ]
+    shown: list[str] = []
+
+    def ask(msg: str, default: str = "") -> str:
+        assert default == "3"  # keep is default
+        return "1"
+
+    key = prompt_menu(
+        "GGUF",
+        items,
+        default="keep",
+        ask=ask,
+        show=shown.append,
+    )
+    assert key == "recommended"
+    assert any("1. rec" in line for line in shown)
+    assert any("←" in line for line in shown)