Classifier: When complexity_threshold is set (e.g. 10), uses it as the
rating scale and maps ratings proportionally to target buckets instead
of 1:1. Formula: idx = rating * len(targets) / (threshold + 1).
With threshold=10 and 3 targets: 1-3→target[0], 4-7→target[1], 8-10→target[2].
Seed: Added 'dispatcher' group (classifier, threshold=10, selector=deepseek-v4-flash)
that auto-routes to fast-flow/standard-pro/heavy-logic by complexity score.
Combined with hierarchical routing, this enables two-level dispatch:
dispatcher scores 1-10 → routes to tier group → tier picks concrete model.