fix(staging): set APP_DEBUG default to false for security

Staging environment should not expose detailed error messages,
stack traces, or debug information to end users.

Changed default from 'true' to 'false' in all services:
- php
- nginx
- queue-worker
- scheduler

docker-compose.staging.yml

@@ -20,7 +20,7 @@ services:
     environment:
       - TZ=Europe/Berlin
       - APP_ENV=staging
-      - APP_DEBUG=${APP_DEBUG:-true}
+      - APP_DEBUG=${APP_DEBUG:-false}
       - APP_URL=https://staging.michaelschiemer.de
       - APP_KEY=${APP_KEY:-}
       # Git Repository - clones staging branch
@@ -210,7 +210,7 @@ services:
     environment:
       - TZ=Europe/Berlin
       - APP_ENV=staging
-      - APP_DEBUG=${APP_DEBUG:-true}
+      - APP_DEBUG=${APP_DEBUG:-false}
       # Git Repository - clones staging branch
       - GIT_REPOSITORY_URL=${GIT_REPOSITORY_URL:-}
       - GIT_BRANCH=staging
@@ -351,7 +351,7 @@ services:
     environment:
       - TZ=Europe/Berlin
       - APP_ENV=staging
-      - APP_DEBUG=${APP_DEBUG:-true}
+      - APP_DEBUG=${APP_DEBUG:-false}
       # Database - using separate staging database
       - DB_HOST=postgres
       - DB_PORT=5432
@@ -406,7 +406,7 @@ services:
     environment:
       - TZ=Europe/Berlin
       - APP_ENV=staging
-      - APP_DEBUG=${APP_DEBUG:-true}
+      - APP_DEBUG=${APP_DEBUG:-false}
       # Database - using separate staging database
       - DB_HOST=postgres
       - DB_PORT=5432