fix(database): prevent React #31 crash when opening models with object values

[kkopanidis]

Summary

Opening a model detail page crashed with React error #31 when a schema default or document field contained a plain object such as { startDate, endDate, nights }. React cannot render objects as children; the UI was passing those values straight into JSX in a few places (and schema field defaults were not normalized for text inputs).

Changes

• Add formatDisplayValue / formatCellDisplayValue / normalizeFieldDefault helpers
• Normalize schema field defaults and types when loading into the schema editor
• Restore JSON/Number/Boolean defaults correctly on save
• Coerce document grid, document panel, relation picker, and filter chip values to strings before render
• Fix createdAt/updatedAt tooltip content that rendered raw cell values

Test plan

• Open a model whose schema has a JSON field with an object default — schema tab should load without crashing; default shows as JSON text
• Open Data for a model with documents containing nested objects like { startDate, endDate, nights } — grid renders a JSON preview badge instead of crashing
• Hover createdAt/updatedAt tooltips — tooltip text is a string
• Open a document with a Relation field and object-valued display fields on related docs — picker labels stay strings
• Edit and save a JSON default — object shape is preserved when valid JSON is entered