analyze: run condor compute jobs via .venv/bin/giant, not uv run

uv isn't installed on the HTCondor worker docker image, so `uv run`
fails there. giant is already an installed console script in the
repo's uv-synced .venv, so exec it directly instead. write_submit now
fails fast with a clear message if .venv/bin/giant is missing.

tests/test_condor.py

@@ -53,6 +53,14 @@ def _write_inputs(tmp_path: Path) -> Path:
     return yaml_path
 
 
+def _fake_venv(repo_dir: Path) -> None:
+    """Stand in for a `uv sync`'d venv: write_submit checks `.venv/bin/giant` exists."""
+    giant = repo_dir / ".venv" / "bin" / "giant"
+    giant.parent.mkdir(parents=True, exist_ok=True)
+    giant.write_text("#!/bin/bash\n")
+    giant.chmod(0o755)
+
+
 def _prep(
     rollout_yaml: Path, run_dir: str | Path | None = None, chunks: int = 1
 ) -> Path:
@@ -166,6 +174,7 @@ def test_compute_reduced_rejects_out_of_range_chunk(tmp_path: Path):
 
 def test_write_submit_description(tmp_path: Path):
     run_dir = _prep(_write_inputs(tmp_path))
+    _fake_venv(tmp_path)
     cfg = SubmitConfig(run_dir=run_dir, accounting_group="cms", repo_dir=tmp_path)
     txt = write_submit(cfg).read_text()
     assert "universe = docker" in txt
@@ -185,8 +194,16 @@ def test_write_submit_description(tmp_path: Path):
     assert "--chunk" in body and "--run-dir" in body
 
 
+def test_write_submit_requires_synced_venv(tmp_path: Path):
+    run_dir = _prep(_write_inputs(tmp_path))
+    cfg = SubmitConfig(run_dir=run_dir, accounting_group="cms", repo_dir=tmp_path)
+    with pytest.raises(FileNotFoundError, match="uv sync"):
+        write_submit(cfg)
+
+
 def test_write_submit_remote_flag(tmp_path: Path):
     run_dir = _prep(_write_inputs(tmp_path))
+    _fake_venv(tmp_path)
     cfg = SubmitConfig(
         run_dir=run_dir, accounting_group="cms", repo_dir=tmp_path, remote=True
     )
@@ -198,6 +215,7 @@ def test_write_submit_remote_flag(tmp_path: Path):
 def test_write_submit_chunks_respect_chunkable(tmp_path: Path):
     assert get_spec("router_gating").chunkable is False
     run_dir = _prep(_write_inputs(tmp_path), chunks=4)
+    _fake_venv(tmp_path)
     cfg = SubmitConfig(
         run_dir=run_dir, accounting_group="cms", repo_dir=tmp_path, n_chunks=4
     )
@@ -227,6 +245,7 @@ def test_write_submit_walltime_grows_with_chunk_rows(tmp_path: Path):
 
     run_dir = _prep(_write_inputs(tmp_path), chunks=2)
     meta = RunMeta.load(run_dir / "run_meta.json")
+    _fake_venv(tmp_path)
     cfg = SubmitConfig(
         run_dir=run_dir, accounting_group="cms", repo_dir=tmp_path, n_chunks=2
     )