config: enhance SPA routing in Caddyfile and add new production logs screenshot

- Refined SPA fallback configuration in `Caddyfile` using `try_files` for improved stability.
- Added production logs screenshot (`prod-docker-logs-web-app_2026-03-12_17-10.png`) to document application state.

Signed-off-by: Stefan Mogeritsch <stefan.mo.co@gmail.com>

config/docker/caddy/web-app/Caddyfile

@@ -57,11 +57,12 @@
                    respond "healthy" 200
                  }
 
-# 3. Static Files & SPA Fallback (NEUE, ROBUSTERE KONFIGURATION)
-# Serve static files directly.
-# For any path that is NOT a file and NOT a directory, rewrite to /index.html.
-# This is a more explicit SPA-fallback than try_files for some proxies.
-  @not_file `not file`
-  rewrite @not_file /index.html
-  file_server
+# 3. Static Files & SPA Fallback (Stable Config)
+  handle {
+         # Serve static files if they exist
+           file_server
+
+         # SPA Routing: Fallback to index.html for non-existent files
+           try_files {path} /index.html
+         }
 }