feat: Upgrade client to Python 3.12/3.13 while maintaining server at Python 3.9

Upgrades the Lokole client (webapp) to Python 3.12/3.13 while keeping the server components at Python 3.9 for Azure compatibility.

Key changes:
- Update Python version in client Dockerfile to 3.12
- Add Python 3.13 support to setup.py
- Upgrade dependencies for Python 3.12/3.13 compatibility
- Fix Azure Service Bus message format
- Improve data URI handling
- Update development tooling and configs

Tested successfully with IIAB integration on Ubuntu 26.04 (Python 3.12.3).

Closes #609

Author: dahagag

.env

@@ -1,7 +1,7 @@
 STATUSPAGE_PORT=3000
 APP_PORT=8080
 CLIENT_PORT=5000
-BUILD_TAG=development
+BUILD_TAG=0.0.0.dev0
 BUILD_TARGET=builder
 DOCKER_REPO=ascoderu
 WEBAPP_WORKERS=1