feat(autofill): copy TOTP to clipboard after credential autofill

[tomhung]

Summary

When autofilling credentials for a resource that has TOTP configured, automatically copy the current TOTP code to the clipboard. This streamlines the login process for 2FA-enabled accounts.

Changes

• Add TotpService to generate TOTP codes using existing jsSHA dependency (RFC 6238)
• Modify AutofillController to copy TOTP after filling credentials
• TOTP is copied with 30-second auto-clear (using existing CopyToClipboardService)
• Silently handles errors to not disrupt autofill if TOTP copy fails

Test plan

• Create a resource with TOTP configured
• Go to a login page matching that resource
• Click the resource to autofill credentials
• Verify TOTP code is now in clipboard (Ctrl+V)
• Verify clipboard auto-clears after 30 seconds

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[CLAassistant]

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