chore: ignore local publish trees; bump explorer-monorepo and smom-dbis-138

- Ignore cross-chain-pmm-lps-publish, smom-dbis-138-publish, thirdweb nested contracts
- Remove stray empty root placeholders (now ignored patterns documented)
- Point submodules at pushed explorer (ee71f09) and contracts (6817f53) commits

Made-with: Cursor

.gitignore

@@ -107,3 +107,15 @@ reconciliation/
 *.payload.json
 *.payload.sha256
 audit_log.jsonl
+
+# Local publish / clone trees (nested git repos; not submodules)
+cross-chain-pmm-lps-publish/
+smom-dbis-138-publish/
+
+# Thirdweb scratch test: vendored contracts dep is a nested clone
+thirdweb-core-2103-test/lib/contracts/
+
+# Stray empty placeholders at repo root (do not track)
+/Arbitrum
+/cWUSDC
+/cWUSDT