Add connection.close event listener to telemetry wire-up

Fix missing event listener for CONNECTION_CLOSE events in DBSQLClient
telemetry initialization. Without this listener, connection close events
were being emitted but not routed to the aggregator for processing.

Now all 3 telemetry events are properly exported:
- CONNECTION_OPEN (connection latency)
- STATEMENT_COMPLETE (execution latency)
- CONNECTION_CLOSE (session duration)

Verified with e2e test showing 3 successful telemetry exports.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: samikshya-db

lib/DBSQLClient.ts

@@ -346,6 +346,14 @@ export default class DBSQLClient extends EventEmitter implements IDBSQLClient, I
         }
       });
 
+      this.telemetryEmitter.on('connection.close', (event) => {
+        try {
+          this.telemetryAggregator?.processEvent(event);
+        } catch (error: any) {
+          this.logger.log(LogLevel.debug, `Error processing connection.close event: ${error.message}`);
+        }
+      });
+
       this.telemetryEmitter.on('statement.start', (event) => {
         try {
           this.telemetryAggregator?.processEvent(event);