fixed system diagram plot (exported to png and updated .md)

Author: HardMax71

README.md

@@ -128,7 +128,7 @@ cause `match-case` was introduced first in `Python 3.10`.
 > [!WARNING]
 > Detailed, up-to-date architecture diagrams are in [this file](files_for_readme/ARCHITECTURE_IN_DETAILS.md).
 
-<img src="./files_for_readme/system_diagram.svg" alt="system diagram">
+<img src="./files_for_readme/system_diagram.png" alt="system diagram">
 
 The platform is built on three main pillars:
 

files_for_readme/ARCHITECTURE_IN_DETAILS.md

@@ -6,7 +6,7 @@ Preciser info about peculiarities of separate components (SSE, Kafka topics, DLQ
 
 ## Top-level system (containers/services)
 
-<img src="./system_diagram.svg" alt="System diagram">
+<img src="./system_diagram.png" alt="System diagram">
 
 The SPA hits the frontend, which proxies to the API over HTTPS; the API
 serves both REST and SSE. Kafka carries events with Schema Registry and Zookeeper backing it; kafka-