Summary

Add image alt text editing popover to the rich text editor and improve the
link settings popover UX to match the sidebar LinkSettings component.

Changes

• Add image alt text popover in the rich text toolbar (opens when clicking an image)
• Add RichTextImageBlock component with selection ring indicator
• Add RichTextImageWithNodeView TipTap extension for proper node selection
• Refactor RichTextLinkPopover to use SettingsPanel with trash/close action buttons
• Apply link changes immediately on edit instead of requiring an Apply button
• Do not preselect URL type for new links, let the user choose
• Use SelectTrigger onClear for link type removal in RichTextLinkSettings
• Add w-full to SelectTrigger base styles
• Adjust ghost button dark mode hover color

Test plan

• In rich text editor, insert an image and click it — selection ring appears and alt text popover opens below the toolbar image button
• Edit alt text in the popover — saves on close/blur
• Click the x button in the image popover — closes and saves
• In rich text editor, select text and click the link button — popover opens with no type preselected
• Choose a link type and configure it — link is applied immediately without needing an Apply button
• Click the trash icon on an existing link — link is removed
• Click the x close button — popover closes
• Use the clear icon inside the link type select to reset to no link
• Verify SelectTrigger fills container width in all select dropdowns