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

docs/operations/troubleshooting.md

@@ -17,6 +17,9 @@ cp .env.example .env
 nano .env
 
 # Required variables:
+# Generate secure passwords (no special characters):
+#   JWT_SECRET: openssl rand -hex 32
+#   DBPASS: openssl rand -hex 16
 JWT_SECRET="your-secure-jwt-secret-key-here"  # 64+ char random string
 DBPASS="your-secure-database-password"        # Strong password