docs(cache): add comprehensive cache configuration and permission handling guides

- Introduce `cache-configuration.md` for detailed instructions on cache setup, permission troubleshooting, and best practices.
- Add `cache-permissions-quick-fix.md` for concise resolutions to common permission errors.
- Include a detailed `FILECACHE_PERMISSION_FIX_PLAN.md` outlining solutions for permission-related issues.
- Enhance `docker-entrypoint.sh` with permission fixes for multi-user caches.
- Update `Makefile` with cache clear commands for local and staging environments.
- Improve `FileCache` for graceful degradation on permission errors, ensuring reliability under multi-user scenarios.

docs/deployment/cache-permissions-quick-fix.md

@@ -0,0 +1,74 @@
+# Cache Permissions Quick Fix
+
+## Problem
+
+```
+chown: invalid user: 'appuser:appuser'
+```
+
+Der User `appuser` existiert nicht im Container, oder es wird ein anderer User verwendet.
+
+## L?sung: Dynamischer Fix
+
+### Schritt 1: Ermittle den korrekten User
+
+```bash
+# Pr?fe welcher User verwendet wird
+docker exec staging-app whoami
+docker exec staging-app id
+
+# Pr?fe PHP-FPM Konfiguration
+docker exec staging-app grep "^user = " /usr/local/etc/php-fpm.d/*.conf
+```
+
+### Schritt 2: Fix Berechtigungen (automatisch)
+
+```bash
+# Automatisch - ermittle User aus PHP-FPM Config
+docker exec -it --user root staging-app bash -c '
+  USER=$(grep "^user = " /usr/local/etc/php-fpm.d/*.conf 2>/dev/null | head -1 | cut -d"=" -f2 | tr -d " ;")
+  [ -z "$USER" ] && USER="www-data"
+  echo "Using user: $USER"
+  chown -R $USER:$USER /var/www/html/storage/cache
+  chmod -R 775 /var/www/html/storage/cache
+'
+```
+
+### Schritt 3: Fix existierende Dateien
+
+```bash
+docker exec -it --user root staging-app bash -c '
+  USER=$(grep "^user = " /usr/local/etc/php-fpm.d/*.conf 2>/dev/null | head -1 | cut -d"=" -f2 | tr -d " ;")
+  [ -z "$USER" ] && USER="www-data"
+  find /var/www/html/storage/cache -type f -exec chmod 644 {} \;
+  find /var/www/html/storage/cache -type d -exec chmod 775 {} \;
+  chown -R $USER:$USER /var/www/html/storage/cache
+  echo "Fixed permissions for user: $USER"
+'
+```
+
+## Alternative: Manuelle Fix
+
+Wenn du wei?t, welcher User verwendet wird:
+
+**F?r `www-data` (Production):**
+```bash
+docker exec -it --user root staging-app chown -R www-data:www-data /var/www/html/storage/cache
+docker exec -it --user root staging-app chmod -R 775 /var/www/html/storage/cache
+```
+
+**F?r `appuser` (Development/Staging):**
+```bash
+docker exec -it --user root staging-app chown -R appuser:appuser /var/www/html/storage/cache
+docker exec -it --user root staging-app chmod -R 775 /var/www/html/storage/cache
+```
+
+## Verifikation
+
+```bash
+# Pr?fe Berechtigungen
+docker exec staging-app ls -ld /var/www/html/storage/cache
+
+# Pr?fe Owner
+docker exec staging-app ls -l /var/www/html/storage/cache | head -5
+```