rename python package projected_grpo -> vgrout

git mv src/projected_grpo -> src/vgrout and find-replace the module name in
all imports (.py), `-m projected_grpo.*` invocations (justfile), and the
[project] name (pyproject; setuptools auto-discovers via where=["src"]).

Left RESEARCH_JOURNAL.md untouched: its commands/paths are dated lab notes
tied to past commits, so rewriting them would falsify provenance. Repo dir,
git remote, and absolute paths unchanged.

Verified: `import vgrout` and `python -m vgrout.train --help` load the full
graph; verify_rewards.py + verify_gate_anchor.py (both import vgrout) pass.
Full `just smoke` is blocked upstream by missing gitignored data artifacts
(out/pools/{substrate,teacher_pool}, out/vhack/*smoke*), unrelated to the rename.

scripts/attic/make_dataset_pairsets.py

@@ -31,8 +31,8 @@ from pathlib import Path
 
 from datasets import load_dataset
 
-from projected_grpo.pairs import HackPair
-from projected_grpo.pairs_from_pool import load_pairs_json, save_pairs_json
+from vgrout.pairs import HackPair
+from vgrout.pairs_from_pool import load_pairs_json, save_pairs_json
 
 OUT = Path("out/pairsets")
 N_PREF = 256       # reward_hack_pref subset size (well-conditioned for k=12, fast extract)

scripts/attic/make_pairsets.py

@@ -31,9 +31,9 @@ from __future__ import annotations
 
 from pathlib import Path
 
-from projected_grpo import pairs as PB
-from projected_grpo.pairs import HackPair, _wrap
-from projected_grpo.pairs_from_pool import save_pairs_json
+from vgrout import pairs as PB
+from vgrout.pairs import HackPair, _wrap
+from vgrout.pairs_from_pool import save_pairs_json
 
 OUT = Path("out/pairsets")
 _IMP = "from typing import List"