fix(document-graph): truncate long text lines in document nodes

Document nodes with long unbroken text (like separator lines with ====)
were bleeding outside their boundaries. Fixed by:
- Setting fixed width (280px) on container instead of just maxWidth
- Using break-all word breaking for description text
- Adding webkit line clamping to limit description to 3 lines
- Using text-overflow: ellipsis with overflow: hidden

src/__tests__/renderer/components/DocumentGraph/DocumentNode.test.tsx

@@ -288,6 +288,19 @@ describe('DocumentNode', () => {
 			const truncatedText = description.slice(0, 100).trim() + '...';
 			expect(screen.getByText(truncatedText)).toBeInTheDocument();
 		});
+
+		it('applies line clamping styles to description for overflow handling', () => {
+			const props = createNodeProps({ description: 'Some description text' });
+
+			renderWithProvider(<DocumentNode {...props} />);
+
+			const descriptionElement = screen.getByText('Some description text');
+			// Should have line clamping and word break styles
+			expect(descriptionElement).toHaveStyle({
+				overflow: 'hidden',
+				wordBreak: 'break-all',
+			});
+		});
 	});
 
 	describe('Selection State', () => {
@@ -370,6 +383,21 @@ describe('DocumentNode', () => {
 		});
 	});
 
+	describe('Container Dimensions', () => {
+		it('has fixed width to prevent overflow from long content', () => {
+			const props = createNodeProps();
+
+			const { container } = renderWithProvider(<DocumentNode {...props} />);
+
+			const nodeElement = container.querySelector('.document-node');
+			expect(nodeElement).toHaveStyle({
+				width: '280px',
+				maxWidth: '280px',
+				overflow: 'hidden',
+			});
+		});
+	});
+
 	describe('Theme Integration', () => {
 		it('uses theme background color', () => {
 			const props = createNodeProps();

src/renderer/components/DocumentGraph/DocumentNode.tsx

@@ -94,6 +94,7 @@ export const DocumentNode = memo(function DocumentNode({ data, selected }: Docum
 			padding: 12,
 			minWidth: 200,
 			maxWidth: 280,
+			width: 280,
 			overflow: 'hidden' as const,
 			boxShadow: isHighlighted
 				? `0 0 0 3px ${theme.colors.accent}40, 0 4px 12px ${theme.colors.accentDim}`
@@ -152,8 +153,12 @@ export const DocumentNode = memo(function DocumentNode({ data, selected }: Docum
 			lineHeight: 1.4,
 			opacity: 0.85,
 			overflow: 'hidden' as const,
-			wordBreak: 'break-word' as const,
-			overflowWrap: 'break-word' as const,
+			textOverflow: 'ellipsis' as const,
+			wordBreak: 'break-all' as const,
+			overflowWrap: 'anywhere' as const,
+			display: '-webkit-box' as const,
+			WebkitLineClamp: 3,
+			WebkitBoxOrient: 'vertical' as const,
 		}),
 		[theme.colors.textDim]
 	);