fix(obs): correct GlitchTip port and healthcheck for v6.x

GlitchTip 6.x moved its internal listen port from 8080 to 8000.
The ports mapping was forwarding to the wrong port (host traffic
never reached the app), and the healthcheck was probing 8080 with
wget (not present in the image), causing the container to stay
permanently unhealthy.

Fix: map to port 8000, check with bash /dev/tcp (no external tools
needed, available in the Python base image).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.observability.yml

@@ -202,9 +202,9 @@ services:
       EMAIL_URL: smtp://mailpit:1025
       GLITCHTIP_MAX_EVENT_LIFE_DAYS: 90
     ports:
-      - "127.0.0.1:${PORT_GLITCHTIP:-3002}:8080"
+      - "127.0.0.1:${PORT_GLITCHTIP:-3002}:8000"
     healthcheck:
-      test: ["CMD-SHELL", "wget -qO- http://localhost:8080/_health/ || exit 1"]
+      test: ["CMD", "bash", "-c", "echo > /dev/tcp/localhost/8000"]
       interval: 30s
       timeout: 10s
       retries: 5