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>

pyproject.toml

@@ -38,11 +38,7 @@ analysis = [
 
 [project.scripts]
 giant = "giant.cli:app"
-steps-to-parquet = "scripts.steps_to_parquet:main"
-steps-to-parquet-parallel = "scripts.steps_to_parquet_parallel:main"
-migrate-geant-steps = "scripts.migrate_geant_steps:main"
-bump-dataset-version = "scripts.bump_dataset_version:main"
-create-root-files = "scripts.create_root_files:main"
+dwarf = "scripts.dwarf:app"
 
 [build-system]
 requires = ["hatchling"]