fix: wire missing DB env vars into worker and step_result lambdas

worker:
  - replace unused RESULTS_QUEUE_URL with input_queue_url (sqs.delete_message)
  - add dbEndpoint, dbUsername, dbDatabase, dbRegion

step_result:
  - add environment block with dbEndpoint, dbUsername, dbDatabase, dbRegion

dispatcher unchanged (no DB access)

lambda.tf

@@ -96,6 +96,15 @@ resource "aws_lambda_function" "step_result" {
     ipv6_allowed_for_dual_stack = false
   }
 
+  environment {
+    variables = {
+      dbEndpoint = aws_rds_cluster.patch4.endpoint
+      dbUsername = local.db_user_name
+      dbDatabase = local.db_name
+      dbRegion   = local.region
+    }
+  }
+
   ephemeral_storage { size = 512 }
   tracing_config { mode = "PassThrough" }
 
@@ -130,7 +139,11 @@ resource "aws_lambda_function" "worker" {
 
   environment {
     variables = {
-      RESULTS_QUEUE_URL = aws_sqs_queue.results.url
+      input_queue_url = aws_sqs_queue.dispatch_lambda.url
+      dbEndpoint      = aws_rds_cluster.patch4.endpoint
+      dbUsername      = local.db_user_name
+      dbDatabase      = local.db_name
+      dbRegion        = local.region
     }
   }