feat: scaffold avatar pipeline with ComfyUI driver, MLflow logging, and rclone promotion

- setup.sh: automated desktop env setup (ComfyUI, 3D-Pack, UniRig, Blender, Ray)
- ray-join.sh: join Ray cluster as external worker with 3d_gen resource label
- vrm_export.py: headless Blender GLB→VRM conversion script
- generate.py: ComfyUI API driver (submit workflow JSON, poll, download outputs)
- log_mlflow.py: REST-only MLflow experiment tracking (no SDK dependency)
- promote.py: rclone promotion of VRM files to gravenhollow S3
- CLI entry points: avatar-generate, avatar-promote
- workflows/ placeholder for ComfyUI exported workflow JSONs

Implements ADR-0063 (ComfyUI + TRELLIS + UniRig 3D avatar pipeline)

avatar_pipeline/promote.py

@@ -0,0 +1,131 @@
+"""Promote VRM files to gravenhollow via rclone.
+
+Usage:
+    avatar-promote exports/Silver-Mage.vrm
+    avatar-promote exports/Silver-Mage.vrm --bucket companion-avatars
+    avatar-promote --dry-run exports/*.vrm
+"""
+
+from __future__ import annotations
+
+import argparse
+import logging
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+logger = logging.getLogger(__name__)
+
+DEFAULT_REMOTE = "gravenhollow"
+DEFAULT_BUCKET = "avatar-models"
+
+
+def check_rclone() -> bool:
+    """Verify rclone is installed and the remote is configured."""
+    if not shutil.which("rclone"):
+        logger.error("rclone not found. Install: sudo pacman -S rclone")
+        return False
+
+    result = subprocess.run(
+        ["rclone", "listremotes"],
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    remotes = result.stdout.strip().split("\n")
+
+    if f"{DEFAULT_REMOTE}:" not in remotes:
+        logger.error(
+            "rclone remote '%s' not configured. Run scripts/setup.sh or configure manually.",
+            DEFAULT_REMOTE,
+        )
+        return False
+
+    return True
+
+
+def promote(
+    files: list[Path],
+    remote: str = DEFAULT_REMOTE,
+    bucket: str = DEFAULT_BUCKET,
+    dry_run: bool = False,
+) -> list[str]:
+    """Copy VRM files to gravenhollow S3 via rclone.
+
+    Returns list of promoted remote paths.
+    """
+    if not check_rclone():
+        raise RuntimeError("rclone not available")
+
+    promoted = []
+    for file_path in files:
+        if not file_path.exists():
+            logger.warning("File not found, skipping: %s", file_path)
+            continue
+
+        if file_path.suffix.lower() not in (".vrm", ".glb", ".fbx"):
+            logger.warning("Unexpected file type, skipping: %s", file_path)
+            continue
+
+        dest = f"{remote}:{bucket}/{file_path.name}"
+        cmd = ["rclone", "copy", str(file_path), f"{remote}:{bucket}/"]
+
+        if dry_run:
+            cmd.append("--dry-run")
+
+        logger.info("Promoting: %s → %s", file_path, dest)
+
+        result = subprocess.run(
+            cmd,
+            capture_output=True,
+            text=True,
+            check=False,
+        )
+
+        if result.returncode != 0:
+            logger.error("rclone failed for %s: %s", file_path, result.stderr)
+            continue
+
+        if dry_run:
+            logger.info("  (dry-run) Would copy %s", file_path.name)
+        else:
+            logger.info("  Promoted: %s", dest)
+
+        promoted.append(dest)
+
+    return promoted
+
+
+def main() -> None:
+    """CLI entry point."""
+    parser = argparse.ArgumentParser(description="Promote VRM files to gravenhollow storage")
+    parser.add_argument("files", nargs="+", type=Path, help="VRM/GLB files to promote")
+    parser.add_argument("--remote", default=DEFAULT_REMOTE, help="rclone remote name")
+    parser.add_argument("--bucket", default=DEFAULT_BUCKET, help="S3 bucket name")
+    parser.add_argument("--dry-run", action="store_true", help="Show what would be copied")
+    parser.add_argument("--verbose", "-v", action="store_true")
+    args = parser.parse_args()
+
+    logging.basicConfig(
+        level=logging.DEBUG if args.verbose else logging.INFO,
+        format="%(asctime)s %(levelname)s %(name)s: %(message)s",
+    )
+
+    try:
+        promoted = promote(
+            files=args.files,
+            remote=args.remote,
+            bucket=args.bucket,
+            dry_run=args.dry_run,
+        )
+        print(f"\nPromoted {len(promoted)} file(s)")
+        for p in promoted:
+            print(f"  {p}")
+    except Exception:
+        logger.exception("Promotion failed")
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()