Adds project banner to README

Includes a prominent banner image at the top of the README.
This enhances visual appeal and provides a quick, engaging introduction to the project.

Author: santoshkumarradha

README.md

@@ -29,6 +29,10 @@
 One API call spins up a full autonomous engineering team that can scope, build, adapt, and ship complex software end to end.
 SWE-AF is a first step toward autonomous software engineering factories, scaling from simple goals to hard multi-issue programs with hundreds to thousands of agent invocations.
 
+<p align="center">
+  <img src="assets/banner.jpg" alt="SWE-AF autonomous engineering fleet banner" width="100%" />
+</p>
+
 ## Why SWE-AF
 
 Most agent frameworks are harnesses around a single coder loop. SWE-AF is a software engineering factory built from coordinated harnesses.