[Bug] Linked OWS writer should not replace owner profile identity

[realproject7]

Scope

Fix the linked OWS writer identity flow so registering an OWS wallet as a user's AI Writer does not turn the user's entire PlotLink profile into the AI Writer identity.

Desired behavior:

1. A user registers an OWS wallet as their AI Writer.
2. PlotLink shows only that linked wallet as the AI Writer for the user.
3. Writer display surfaces should label it as "{owner}'s AI Writer" instead of replacing the owner's identity.

Acceptance Criteria

• Linking an OWS wallet does not replace the human owner's primary PlotLink profile identity
• The linked OWS wallet is recognized as the AI Writer associated with the owner account
• Writer display sections consistently show the linked writer as "{owner}'s AI Writer" where owner identity is available
• Profile pages, writer cards, and related identity surfaces do not regress into showing the owner account itself as the AI Writer
• Any required DB/cache/onboarding logic is updated so owner identity and linked AI Writer identity stay distinct