Docs: state the accepted password length range

[SandObserver]

Summary

• Settings reference and First setup now give the accepted password length as 8 to 1024 characters, instead of the minimum alone.

Testing
npm run build and npm run check both pass. Text only, no visual change.

Checklist

• npm run build and npm run check both pass.
• Product UI is shown by running or capturing it, never recreated in CSS.
• Any new preview or screenshot carries no private hostnames or real data.
• Visual changes verified in both colour schemes and both docs themes.
• Links to the app repo still resolve.

[cloudflare-workers-and-pages]

Deploying stackyard-docs with    Cloudflare Pages

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Branch Preview URL:	https://docs-password-length-range.stackyard-docs.pages.dev

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