feat: CMS tabs layout field with field-level permissions and rules

[Pavel910]

Summary

• Introduce a Tabs layout field for CMS content models — allows grouping data fields into tabs in the entry editor
• Add field-level permissions and per-tab permission control so access can be restricted per field/tab
• Add field rules system (stored as a single rules array) for conditional field visibility/behavior
• Separate DataFieldBuilder and LayoutFieldBuilder to cleanly distinguish data-bearing fields from UI-only layout fields (tabs, separator, alert)
• Support drag & drop for layout fields
• Update all field renderers to support a disabled prop for permission-driven read-only mode
• Add drawer-based field edit dialog, entries refresh button, and panorama viewer
• Minor fixes: lexical link autofocus, fieldId zod validation, content model error reporting, list view heading styling

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