Report missing asset leaves and add opt-in strict mode (#421)

docs/history/0.2.3.md

@@ -87,3 +87,12 @@ Only that granted trait additionally listens to `dollSwap`, in both directions,
 Deployment and switches share the original cap, active-bond checks and grant deduplication. Other deployment
 traits keep their existing triggers. The 7 regression cases cover both real dollkeepers, natural and S2 returns,
 shared caps, duplicate grant holders, inactive bonds and unrelated timed windows.
+
+### 28.6 Asset download visibility — PR #421
+
+Ported from [PR #421](https://github.com/sganggs/Stronghold-Protocol/pull/421) by @LimitlessHPPK.
+The asset resolver records every planned leaf with no alternative on disk as `droppedLeaves` in its report;
+the terminal prints a bounded summary. `--strict` / `SP_ASSETS_STRICT=1` returns exit 1 for those omissions.
+The default remains a warning, and the existing manifest shrink guard remains in force. Strict mode changes
+the outcome code; it is not a transaction and does not roll back a manifest already written. Temporary test
+assets are cleaned up after each case. This is an opt-in tool check, not an added packaging requirement.