fix(lint): flatten max-depth in storeTcTokensFromHistorySync

CI lint failed with:
  process-message.ts:127:6 error Blocks are nested too deeply (5). Maximum allowed is 4 max-depth

The previous shape nested `if (pnsToResolve.length) → try → if (mappings) → for → if (pn && lid)` = 5 levels. Flattened to 4 by:
- Using `mappings ?? []` so the for-of can iterate without an outer guard
- Inverting the inner predicate to `if (!pn || !lid) continue`

No behavior change. CI should now pass.

src/Utils/process-message.ts

@@ -122,10 +122,10 @@ async function storeTcTokensFromHistorySync(
 	if (pnsToResolve.length) {
 		try {
 			const mappings = await signalRepository.lidMapping.getLIDsForPNs(pnsToResolve)
-			if (mappings) {
-				for (const { pn, lid } of mappings) {
-					if (pn && lid) pnToLid.set(jidNormalizedUser(pn), lid)
-				}
+			// Flat loop (continue-on-skip) keeps max nesting depth at 4 for lint.
+			for (const { pn, lid } of mappings ?? []) {
+				if (!pn || !lid) continue
+				pnToLid.set(jidNormalizedUser(pn), lid)
 			}
 		} catch (err) {
 			// Per-chat fallback below (storageJid := jid). Don't abort the chunk —