[Exchange] Research and select blockchain/L2 for agent wallet infrastructure done

{
  "completion_shas": [
    "1c55fe579df51464f6ba590ac3164b39979ed95e"
  ],
  "completion_shas_checked_at": "2026-04-17T10:44:53.391599+00:00",
  "_reset_note": "This task was reset after a database incident on 2026-04-17.\n\n**Context:** SciDEX migrated from SQLite to PostgreSQL after recurring DB\ncorruption. Some work done during Apr 16-17 may have been lost.\n\n**Before starting work:**\n1. Check if the task's goal is ALREADY satisfied (run the relevant checks)\n2. Check `git log --all --grep=task:YOUR_TASK_ID` for prior commits\n3. If complete, verify and mark done. If partial, continue. If not done, proceed.\n\n**DB change:** SciDEX now uses PostgreSQL. `get_db()` auto-detects via\nSCIDEX_DB_BACKEND=postgres env var.",
  "_reset_at": "2026-04-18T06:29:22.046013+00:00",
  "_reset_from_status": "done"
}