Increase DuckLake max retry count to 100 for concurrent connections

DuckLake uses optimistic concurrency control - when multiple connections
try to commit simultaneously, they may conflict on snapshot IDs in the
PostgreSQL metadata store. The default retry count of 10 is too low for
tools like Fivetran that open many concurrent connections.

This was causing errors like:
"Failed to commit DuckLake transaction. Exceeded maximum retry count of 10.
duplicate key value violates unique constraint ducklake_snapshot_pkey"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: EDsCODE

server/server.go

@@ -406,6 +406,16 @@ func (s *Server) attachDuckLake(db *sql.DB) error {
 	}
 
 	log.Printf("Attached DuckLake catalog successfully")
+
+	// Set DuckLake max retry count to handle concurrent connections
+	// DuckLake uses optimistic concurrency - when multiple connections commit
+	// simultaneously, they may conflict on snapshot IDs. Default of 10 is too low
+	// for tools like Fivetran that open many concurrent connections.
+	if _, err := db.Exec("SET ducklake_max_retry_count = 100"); err != nil {
+		log.Printf("Warning: failed to set ducklake_max_retry_count: %v", err)
+		// Don't fail - this is not critical, DuckLake will use its default
+	}
+
 	return nil
 }