Summary

Add date and number format presets for inline CMS variables, allowing users to choose how dates and numbers are displayed (e.g. "Oct 23, 2025", "23/10/2025", "100%", "1,234.56"). Formatting is applied consistently across the canvas editor, preview mode, and published pages using the user's configured timezone.

Changes

• Add variable-format-utils.ts with date/number format presets using Intl.DateTimeFormat and Intl.NumberFormat
• Add VariableFormatSelector popover component for selecting format presets on inline variable badges
• Add dynamic-variable-view.tsx shared factory to eliminate duplicate DynamicVariable NodeView code between RichTextEditor and CanvasTextEditor
• Extract buildFieldVariableData helper to deduplicate variable construction across 3 components
• Thread formatFieldValue with format preset through all rendering paths (canvas, preview, HTML export)
• Thread user timezone setting through server-side format rendering to respect configured timezone
• Fix variable overwrite bug in injectCollectionData where ...layer.variables spread could clobber already-resolved text when resolving image/video/audio bindings

Test plan

• Add a date inline variable — verify default format is applied ("date-long")
• Click the variable badge to open format selector — verify grouped sections (Date & time, Date, Time)
• Select different date formats and confirm they render correctly on canvas
• Add a number inline variable — verify default format ("integer") and selector shows number formats
• Open preview — verify formatting matches the canvas
• Publish and verify formatting on the genege
• Change the timezone setting and confirm dates shift accordingly on preview/published pages
• Test a layer with both text and image CMS bindings — verify both resolve correctly (regression for the overwrite fix)