Rename threads to smiths

[use-tusk[bot]]

This pull request addresses the task of renaming all user-visible instances of 'threads' to 'smiths' across the application. This involves several changes in different parts of the app including components, configuration files, and server-side code.

The updates include:

• Metadata updates in layout.tsx
• Logo alt text in loading.tsx
• UI text in [profile]/(username)/page.tsx, seed/page.tsx, account-setup-form.tsx, user-profile-card.tsx, user-details.tsx
• Site configuration in site.ts
• Welcome message in auth.ts

These changes only affect visible text and metadata but do not alter any functionality.

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