feat: add ledger backfill command

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

trex_core/application/ledger_outbox.py

@@ -205,6 +205,13 @@ class LedgerWriter:
                 stats.delivery_failed += 1
         return stats
 
+    def process_correlation_id(self, correlation_id: str) -> OutboxOutcome | None:
+        """Process one specific outbox row immediately."""
+        item = self._outbox.get(correlation_id)
+        if item is None:
+            return None
+        return self._process(item)
+
     def _backoff_delay(self, attempts: int) -> float:
         """Exponential backoff with jitter: min(base*2^(n-1), cap) + up to 25%."""
         base_delay = min(self._retry_base * (2 ** (attempts - 1)), self._retry_cap)