feat: implement support-weighted prototype aggregation

configs/experiments/experiment_protocol.yaml

@@ -18,10 +18,16 @@ non_iid:
   num_clients: 10                    # matches PROTEAN paper cross-silo setting
 
 aggregation:
-  # Baseline checkpoint: only the reproduced original-PROTEAN aggregation is
-  # implemented. Support-weighted beta candidates and the equal_available control
-  # are DEFERRED to the later beta/controls phase (see docs/research/EXPERIMENT_PROTOCOL.md).
+  # Both the reproduced original-PROTEAN aggregation and the proposed
+  # class-specific sample-support weighting are implemented. The proposed mode is
+  # selected with `support_weighted` plus a beta in [0, 1]; the same participant
+  # set S_j is used by both. See docs/research/BETA_AGGREGATION_IMPLEMENTATION.md.
   baseline_mode: original_protean
+  modes: [original_protean, support_weighted]
+  support_weighting: class_specific_sample_support
+  beta_candidates: [0.00, 0.25, 0.50, 0.75, 1.00]
+  beta_range: [0.0, 1.0]
+  selection_metric: rare_class_macro_f1
 
 training:
   rounds: 10