A consent checkbox and notice text in subscribe forms

Subscribe forms now support notice text with rich text and an optional consent checkbox. Form, layout, and translation fixes cover the rest.

• Added subscribe form notice text with rich text support and an optional consent checkbox.
• Improved form styling inside content areas, including better button alignment for form layouts.
• Improved heading wrapping with balanced text.
• Applied the theme accent color to native form controls in content areas.
• Fixed search block alignment issues in rendered layouts.
• Fixed stacked author image presentation on post cards and post pages.
• Fixed untranslated interface strings in exported themes.
• Fixed mobile menu logo focus outline.
• Fixed section card columns hiding when a background image is enabled.