feat: ObjectGrid cell type rendering — select Badge colors, date relative format, boolean null handling

- SelectCellRenderer: priority semantic color auto-detection (Critical→red, High→orange, Medium→yellow, Low→gray), muted default for unconfigured colors
- DateCellRenderer: relative format by default, overdue red text styling, ISO tooltip
- BooleanCellRenderer: null/undefined renders as — instead of unchecked checkbox
- ObjectGrid: auto-generates field options from data for inferred select columns
- formatRelativeDate: threshold tightened from 30 to 7 days
- 40 new unit tests for cell renderers and formatRelativeDate edge cases
- ROADMAP.md updated with Module 4 completion details

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

ROADMAP.md

@@ -810,6 +810,9 @@ The `FlowDesigner` is a canvas-based flow editor that bridges the gap between th
 - [x] `formatRelativeDate()` function added for relative time display ("Today", "2 days ago", "Yesterday")
 - [x] DataTable/VirtualGrid header styling unified: `text-[11px] font-semibold uppercase tracking-wider text-muted-foreground/70 bg-muted/30`
 - [x] Remaining hardcoded gray colors in ObjectGrid loading spinner and status badge fallback replaced with theme tokens
+- [x] Select/status type Badge rendering — `getCellRenderer()` returns `<Badge>` with color mapping from `field.options`; auto-generated options from unique data values when type is inferred; priority semantic colors (Critical→red, High→orange, Medium→yellow, Low→gray); muted default style for unconfigured colors
+- [x] Date type human-readable formatting — `DateCellRenderer` defaults to relative format ("Today", "Yesterday", "3 days ago"); overdue dates styled with red text; ISO timestamp shown as hover tooltip; `formatRelativeDate()` threshold tightened to 7 days
+- [x] Boolean type visual rendering — `BooleanCellRenderer` renders `<Checkbox disabled>` for true/false; null/undefined values display as `—`
 
 **ConfigPanelRenderer:**
 - [x] `<Separator>` added between sections for visual clarity

packages/fields/src/__tests__/boolean-checkbox.test.tsx

@@ -36,17 +36,15 @@ describe('BooleanCellRenderer', () => {
     expect(checkbox).toHaveAttribute('data-state', 'unchecked');
   });
 
-  it('should render an unchecked checkbox for null/undefined values', () => {
+  it('should render dash for null/undefined values', () => {
     render(
       <BooleanCellRenderer
         value={null}
         field={{ name: 'active', type: 'boolean' } as any}
       />
     );
 
-    const checkbox = screen.getByRole('checkbox');
-    expect(checkbox).toBeInTheDocument();
-    expect(checkbox).toHaveAttribute('data-state', 'unchecked');
+    expect(screen.getByText('—')).toBeInTheDocument();
   });
 
   it('should render checkbox as disabled (non-interactive)', () => {