Add fluksio status, and ask for a run's parameters at a terminal

Two halves of the same gap: the CLI could start work but not show you any.

`fluksio status` draws the home screen's top half in a terminal — health and
what is wrong with it, every flow with its state and node count, and the
recent runs and failures under them. `--watch` keeps it there. Rich does the
drawing; it was already installed under fastapi's own CLI, and is named now
because a command depends on it.

`fluksio run` with no parameters at a terminal asks for them, one line per
declared input with its declared value in brackets — so Enter through the lot
is what running the defaults looks like, and an artifact input takes the
`@run:` spelling the engine now resolves. A scripted run is untouched: passing
any parameter, or piping the command, skips the questions, as does --defaults.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019V5bsYGNxcgPs4xXmTPx69

backend/tests/test_cli.py

@@ -255,3 +255,53 @@ def test_ctrl_c_while_waiting_cancels_the_run(monkeypatch) -> None:
     args = _parser().parse_args(["run", "train", "--local", "--no-sync"])
     assert cli.cmd_run(args, []) == 130
     assert cancelled == ["run-1"]
+
+
+def test_an_artifact_input_may_be_named_rather_than_pasted() -> None:
+    """The engine resolves either spelling; the CLI just stops mangling them."""
+    import json
+
+    from fluksio.sdk.cli import _coerce
+
+    assert _coerce("@run:123-abc.dataset", "artifact") == "@run:123-abc.dataset"
+    digest = "sha256:" + "a1" * 32
+    assert _coerce(digest, "artifact") == digest
+    # A reference a script already holds still arrives as the object it is.
+    reference = {"digest": digest, "size": 3}
+    assert _coerce(json.dumps(reference), "artifact") == reference
+
+
+def test_the_run_prompt_keeps_declared_values_for_anything_left_blank() -> None:
+    """Enter through the lot is what running with the defaults looks like."""
+    from unittest.mock import patch
+
+    from fluksio.sdk.cli import _ask_params
+
+    definition = {
+        "inputs": [
+            {"spec": {"name": "lr", "dtype": "float"}, "initial": 0.05},
+            {"spec": {"name": "epochs", "dtype": "int"}, "initial": 10},
+        ]
+    }
+
+    with patch("builtins.input", side_effect=["", ""]):
+        # Nothing sent: an input the caller leaves out keeps what it declares,
+        # which is the same contract the browser's dialog has.
+        assert _ask_params(definition) == {}
+
+    with patch("builtins.input", side_effect=["0.01", "50"]):
+        assert _ask_params(definition) == {"lr": 0.01, "epochs": 50}
+
+
+def test_the_run_prompt_names_an_answer_of_the_wrong_type() -> None:
+    from unittest.mock import patch
+
+    import pytest
+
+    from fluksio.sdk import SyncError
+    from fluksio.sdk.cli import _ask_params
+
+    definition = {"inputs": [{"spec": {"name": "lr", "dtype": "float"}}]}
+    with patch("builtins.input", side_effect=["fast"]):
+        with pytest.raises(SyncError, match="lr"):
+            _ask_params(definition)