feat(serving): replace MLflow run logging with native trace spans

Convert ml-serving from isolated MLflow runs to nested traces using
mlflow.start_span_no_context(). The recommend endpoint now emits a full
span tree: recommend (CHAIN) → build_context (TOOL), agent:* (AGENT) ×N,
llm_orchestrator (LLM). Compute and infer endpoints each emit a single span.

Supporting changes:
- mlflow-skinny>=3.1.0 added to requirements
- MLflow configured with --serve-artifacts + mlflow-artifacts:/ default root
  for cross-container artifact proxy (spans now persist from ml-serving)
- --allowed-hosts extended to include mlflow:5000 (SDK includes port in Host)
- science_destiny slider wired through prompts.py and recommend endpoint
- Config page exposes science/destiny slider (0=data-driven, 100=intuitive)
- Tip page shows rationale inline on tap

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

infra/docker/Dockerfile.admin

@@ -1,7 +1,8 @@
 # syntax=docker/dockerfile:1.7
 
 FROM node:22-slim AS base
-RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates \
+RUN apt-get update && apt-get install -y --no-install-recommends \
+      python3 make g++ ca-certificates \
  && rm -rf /var/lib/apt/lists/* \
  && npm install -g pnpm
 ENV CI=true \

infra/docker/docker-compose.yml

@@ -112,11 +112,13 @@ services:
     command: >
       mlflow server
       --backend-store-uri sqlite:////mlflow/mlflow.db
-      --default-artifact-root /mlflow/artifacts
+      --artifacts-destination /mlflow/artifacts
+      --serve-artifacts
+      --default-artifact-root mlflow-artifacts:/
       --host 0.0.0.0
       --port 5000
       --static-prefix /mlflow
-      --allowed-hosts o.alogins.net,localhost
+      --allowed-hosts o.alogins.net,localhost,localhost:5000,mlflow,mlflow:5000
       --cors-allowed-origins https://o.alogins.net
     volumes:
       - /mnt/ssd/dbs/oo/mlflow:/mlflow