fix(frontend): sync provisioned INBOX when master password is set

[whoalin1]

Summary

Provisioned accounts on passwordless (OIDC/SAML) sessions skipped INBOX auto-refresh even when provisioning used a master password. syncInboxes / unified syncEnvelopes treated every provisioningId as disabled whenever password-is-unavailable was true (#7616), which predates master password support (#9008 / #9653).

• Respect masterPasswordEnabled in the store isDisabled predicate (same idea as Navigation).
• Fix Navigation's inverted check and wire master-password-enabled from PageController into the store so the flag is actually set.

Closes #13807

Test plan

• Provisioning with "Use master password" + user_oidc login: stay on INBOX; external mail appears within the background sync interval without folder switch/reload
• Passwordless session without master password: provisioned account still disabled in nav; sync still skipped (requests would fail)
• Password login (non-OIDC): INBOX sync unchanged
• tests/Unit/Controller/PageControllerTest.php passes

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AI disclosure

This PR was drafted with the help of AI coding assistants (Cursor agents / LLM-based tools), including the description. I am responsible for it and happy to rework anything that doesn't fit.

All commits carry an Assisted-by: Cursor:grok-4.7 trailer.

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