🎯 Submission Dry-Run — candidate selection & median BPB

[gHashTag]

Task

Execute dry-run submission pipeline without final submit call.

Requirements

• Run `trios-submit` in dry-run mode
• Collect median BPB from 5 seeds
• Select candidate: min(median_bpb) across seeds
• Validate candidate size < 16MB
• Generate submission manifest JSON

Output

• `artifacts/submission/median_report.json`:
  ```json
  {
  "seeds": [42,43,44,45,46],
  "bpbs": [1.12, 1.08, 1.14, 1.09, 1.11],
  "median": 1.11,
  "mad": 0.02,
  "candidate_seed": 43,
  "candidate_bpb": 1.08
  }
  ```
• `artifacts/submission/candidate.bin`

Acceptance

• Dry-run completes without submit call
• Median BPB < 1.15 threshold
• Candidate selected by min median metric
• Manifest includes all metadata

Part of: 🏆 EPIC: Parameter Golf Submission — Trinity + GF16

Blocker: #530 One-Shot: trios-submit