docs: update password generation to use hex encoding

Change openssl rand commands from base64 to hex encoding to avoid
special characters that break URL parsing in database connection strings.

- JWT_SECRET: openssl rand -hex 32
- DBPASS: openssl rand -hex 16

Updated in:
- .env.example
- README.md
- docs/contributing/DEVELOPMENT.md
- docs/operations/troubleshooting.md

.env.example

@@ -3,9 +3,11 @@
 # Only secrets are required - all other settings have defaults in docker-compose.yml
 
 # JWT Secret for authentication (generate a secure random string)
+# Generate with: openssl rand -hex 32
 JWT_SECRET=your-secure-jwt-secret-key-here
 
 # PostgreSQL database password
+# Generate with: openssl rand -hex 16
 DBPASS=your-secure-database-password-here
 
 # Optional: Override Defaults (defaults are set in docker-compose.yml)