High memory usage in devnet3 (zeam_0 at ~97%)

## Memory Usage Issue - devnet3

Observed during devnet3 run starting **2026-03-09 15:29:40**.

### Metrics

zeam_0 is showing **96.9% memory usage**, significantly higher than all other clients in the same devnet:

| Client | Memory Usage |
|--------|--------------|
| zeam_0 | **96.9%** |
| lantern_0 | 42.2% |
| grandine_0 | 24.4% |
| qlean_0 | 16.3% |
| ethlambda_0 | 19.7% |
| ream_0 | 9.7% |

zeam_0 also has the highest disk usage at **22.6%**.

### Environment

- Network: blockblaz/zeam:devnet3
- Commit: `be6c432ba14b44025b7f49c6e2d400a4cb555fde`
- Start time: 2026-03-09 15:29:40
- Head slot at time of observation: ~15958
- Latest finalized slot: 2687

### Impact

Memory pressure at this level risks OOM kills and instability during longer devnet runs. Needs investigation into potential memory leaks or unbounded growth (possibly in block/state caching, attestation pool, or historical data retention).

### Reported by

@ch4r10t33r via zeam community Telegram