feat(analytics): Plausible über PLAUSIBLE_ENABLED und PLAUSIBLE_HOST steuerbar

Runtime-Konfiguration im Frontend-Container trennt Prod und Staging;
Staging deaktiviert Analytics standardmäßig.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/docker-entrypoint.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+set -eu
+
+PLAUSIBLE_ENABLED="${PLAUSIBLE_ENABLED:-true}"
+PLAUSIBLE_HOST="${PLAUSIBLE_HOST:-https://plausible.elpatron.me}"
+PLAUSIBLE_HOST="${PLAUSIBLE_HOST%/}"
+
+case "$(printf '%s' "$PLAUSIBLE_ENABLED" | tr '[:upper:]' '[:lower:]')" in
+  true|1|yes)
+    PLAUSIBLE_ENABLED_JSON=true
+    PLAUSIBLE_CSP=" ${PLAUSIBLE_HOST}"
+    ;;
+  *)
+    PLAUSIBLE_ENABLED_JSON=false
+    PLAUSIBLE_CSP=""
+    ;;
+esac
+
+export PLAUSIBLE_CSP
+envsubst '${PLAUSIBLE_CSP}' < /etc/nginx/templates/default.conf.template > /etc/nginx/conf.d/default.conf
+
+cat > /usr/share/nginx/html/runtime-config.json <<EOF
+{"plausibleEnabled":${PLAUSIBLE_ENABLED_JSON},"plausibleHost":"${PLAUSIBLE_HOST}"}
+EOF
+
+exec nginx -g 'daemon off;'