Editor: fix invalid patterns

[t-hamano]

Trac ticket: https://core.trac.wordpress.org/ticket/64589

Follow-up to https://core.trac.wordpress.org/changeset/61609

Use of AI Tools

None

Description

This PR fixes the following two invalid patterns:

• Navigation Overlay: This pattern doesn't have an explicit link color, which makes the text invisible in dark themes. This was fixed in Gutenberg (Navigation overlay: fix default pattern contrast issue on dark themes gutenberg#74979) but not yet backported to core.
• Overlay with site info and CTA: The block is broken because one } is missing.

Testing Instructions

• Activate Twenty Twnty-Five
• Go to Appearance > Editor > Global Styles > Styles
• Choose the dark theme "Evening"
• Go to Design > Patterns
• Click the "Add Pattern" button and select "Add Template Part"
• Select the "Navigation Overlay" area and create a template part

Navigation Overlay

Before	After

Overlay with site info and CTA

Before	After

[github-actions]

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