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/contributing/DEVELOPMENT.md

@@ -190,6 +190,9 @@ go test ./... -v
 podman-compose up --build
 
 # Option 2: Direct Go run (requires local PostgreSQL)
+# Generate secure passwords (no special characters):
+#   JWT_SECRET: openssl rand -hex 32
+#   DBPASS: openssl rand -hex 16
 export JWT_SECRET="your-dev-secret"
 export DBPASS="your-db-password"
 go run cmd/server/main.go
@@ -345,8 +348,8 @@ podman-compose build --no-cache
 ### Environment Variables
 
 Required for production:
-- `JWT_SECRET` - 64-byte random string
-- `DBPASS` - Strong database password
+- `JWT_SECRET` - 64-byte random string (generate: `openssl rand -hex 32`)
+- `DBPASS` - Strong database password (generate: `openssl rand -hex 16`)
 - `BASE_URL` - Public URL (e.g., https://bookhoard.example.com)
 
 Optional: