style: revamp connection status popups

[7w1]

Description

For sliding sync with progress indicator, other status (Connecting/connection lost) use the same:

On windows it appears in the title bar like the other connection statuses.

Combined the popup banners into some shared styling and made them appear one after the other instead of being everywhere. Also swapped the update prompts to use that banner instead of native popups since native popups tend to be more intrusive.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

AI disclosure:

• Partially AI assisted (clarify which code was AI assisted and briefly explain what it does).
• Fully AI generated (explain what all the generated code does in moderate detail).

[github-actions]

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Status	Preview URL	Commit	Alias	Updated (UTC)
✅ Deployment successful!	https://pr-1200-sable.raspy-dream-bb1d.workers.dev	e0b710f	pr-1200	Wed, 22 Jul 2026 04:23:59 GMT