- Add sim.input_length_{min,max} (+ CLI overrides) that drop requests
outside the bucket after trace load, enabling per-bucket ablation
(e.g. 0-40k) without rewriting the trace file. Applied uniformly in
both `run`/`ablate` driver path and `oracle` analysis.
- Add cache_score_strong router (alpha=1, beta=1) to isolate how much
of cache_affinity's win is reproducible by just retuning beta in the
existing cache_score framework (no rendezvous, no meta-store bonus).
- Add --auto-instances to ablate: sweeps --auto-candidates ascending
with --auto-probe-router and picks the smallest cluster size whose
TTFT mean <= --auto-target-ttft-mean. Per-candidate calibration
results are persisted under runs/<output_dir>/auto_instances/ so the
pick is auditable; the chosen N is then used for the whole ablation.
