Unify dataset/tooling scripts into a single dwarf Typer CLI

Replace the five separately-hyphenated uv entry points (steps-to-parquet,
steps-to-parquet-parallel, migrate-geant-steps, bump-dataset-version,
create-root-files) plus the unregistered hparam_scan.py with one `dwarf`
command exposing convert/migrate/bump-gen/bump-schema/status/
update-manifest/create-manifest/make-root/hparam-scan as subcommands.

Each scripts/*.py module now only holds argparse-free business logic;
scripts/dwarf.py wires it up with Typer, matching giant/cli.py's style.
`dwarf convert` merges the old serial/parallel conversion scripts behind
a --jobs flag (default 1: sequential with plain -o; >1: dataset-layout
fan-out via subprocess).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/test_dwarf.py

@@ -0,0 +1,68 @@
+from typer.testing import CliRunner
+
+from scripts.dwarf import app
+
+runner = CliRunner()
+
+
+def test_convert_rejects_jobs_below_one(tmp_path):
+    root_file = tmp_path / "shard.root"
+    root_file.touch()
+    result = runner.invoke(app, ["convert", str(root_file), "--jobs", "0"])
+    assert result.exit_code != 0
+    assert "--jobs must be >= 1" in result.output
+
+
+def test_convert_rejects_output_with_multiple_files(tmp_path):
+    a = tmp_path / "a.root"
+    b = tmp_path / "b.root"
+    a.touch()
+    b.touch()
+    result = runner.invoke(app, ["convert", str(a), str(b), "--output", "out.parquet"])
+    assert result.exit_code != 0
+    assert "--output can only be used with a single input file" in result.output
+
+
+def test_convert_rejects_output_with_parallel_jobs(tmp_path):
+    root_file = tmp_path / "shard.root"
+    root_file.touch()
+    result = runner.invoke(
+        app, ["convert", str(root_file), "--output", "out.parquet", "--jobs", "2"]
+    )
+    assert result.exit_code != 0
+    assert "--output cannot be combined with --jobs > 1" in result.output
+
+
+def test_convert_default_jobs_is_one():
+    result = runner.invoke(app, ["convert", "--help"])
+    assert result.exit_code == 0
+    assert "default: 1" in result.output
+
+
+def test_bump_gen_requires_reason():
+    result = runner.invoke(app, ["bump-gen"])
+    assert result.exit_code != 0
+    assert "reason" in result.output.lower()
+
+
+def test_create_manifest_requires_exactly_one_of_output_or_pool(tmp_path):
+    f = tmp_path / "a.parquet"
+    f.touch()
+    result = runner.invoke(app, ["create-manifest", str(f)])
+    assert result.exit_code != 0
+    assert "exactly one of --output or --pool is required" in result.output
+
+
+def test_create_manifest_requires_type_with_pool(tmp_path):
+    f = tmp_path / "a.parquet"
+    f.touch()
+    result = runner.invoke(app, ["create-manifest", "--pool", "pbwo4", str(f)])
+    assert result.exit_code != 0
+    assert "--type is required when --pool is given" in result.output
+
+
+def test_status_reports_missing_root(tmp_path):
+    missing = tmp_path / "does-not-exist"
+    result = runner.invoke(app, ["status", "--root", str(missing)])
+    assert result.exit_code != 0
+    assert "is not a directory" in result.output