fix(ci): fix health check timeout and per-profile MCP server URL routing

The Nextcloud health check expected HTTP 401 from serverinfo, but NC 32
returns 200 — causing 5-minute timeouts. Switch to /status.php with
"installed":true check (matches Docker healthcheck). Also route the
correct MCP_SERVER_URL per CI matrix profile into the app container so
Astrolabe connects to the right service, and make the init script
gracefully skip when the var is unset.

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

app-hooks/post-installation/25-configure-mcp-server-url.sh

@@ -4,9 +4,10 @@
 
 set -e
 
-# The MCP multi-user BasicAuth service runs on port 8000 inside the container
-# From Nextcloud's perspective (inside Docker network), we reach it via service name
-MCP_SERVER_URL="${MCP_SERVER_URL:-http://mcp-multi-user-basic:8000}"
+if [ -z "${MCP_SERVER_URL:-}" ]; then
+  echo "MCP_SERVER_URL not set, skipping Astrolabe MCP server URL configuration"
+  exit 0
+fi
 
 echo "Configuring MCP server URL: $MCP_SERVER_URL"