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)

renovate.json

@@ -0,0 +1,7 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "local>daviestechlabs/renovate-config",
+    "local>daviestechlabs/renovate-config:python"
+  ]
+}