Make onboarding reruns preserve existing config

Co-Authored-By: Paperclip <noreply@paperclip.ing>

docs/cli/setup-commands.md

@@ -33,6 +33,8 @@ Interactive first-time setup:
 pnpm paperclipai onboard
 ```
 
+If Paperclip is already configured, rerunning `onboard` keeps the existing config in place. Use `paperclipai configure` to change settings on an existing install.
+
 First prompt:
 
 1. `Quickstart` (recommended): local defaults (embedded database, no LLM provider, local disk storage, default secrets)
@@ -50,6 +52,8 @@ Non-interactive defaults + immediate start (opens browser on server listen):
 pnpm paperclipai onboard --yes
 ```
 
+On an existing install, `--yes` now preserves the current config and just starts Paperclip with that setup.
+
 ## `paperclipai doctor`
 
 Health checks with optional auto-repair: