feat: a table that may not break between rows moves whole

ODF style:may-break-between-rows="false" — probed: LibreOffice leaves four
lines of a page empty rather than split such a table, and splits the identical
one when the attribute says "true". pageBreaks now emits a single atomic leaf
for the wrapper unless the table is taller than a page, where the rule cannot
be met. Imported, exported and round-tripped; Word has no equivalent.

tests/unit/table-keep-rows.test.ts

@@ -0,0 +1,33 @@
+// ODF style:may-break-between-rows="false": the table moves whole rather than break.
+import { describe, it, expect } from 'vitest';
+import { unzipSync, strFromU8 } from 'fflate';
+import { buildOdt } from '../../src/lib/export/odt';
+import { importOdt } from '../../src/lib/import/odt';
+
+type N = any;
+
+const cell = (text: string): N => ({
+  type: 'tableCell',
+  content: [{ type: 'paragraph', content: [{ type: 'text', text }] }],
+});
+const table = (attrs: N): N => ({
+  type: 'table',
+  attrs,
+  content: [0, 1].map((r) => ({ type: 'tableRow', content: [cell(`a${r}`), cell(`b${r}`)] })),
+});
+
+describe('table keep-rows', () => {
+  it('round-trips style:may-break-between-rows', async () => {
+    const doc: N = { type: 'doc', content: [table({ keepRows: true })] };
+    const bytes = await buildOdt(doc, undefined, 'portrait');
+    expect(strFromU8(unzipSync(bytes)['content.xml'])).toContain('style:may-break-between-rows="false"');
+    expect(importOdt(bytes).content.content?.[0]?.attrs?.keepRows).toBe(true);
+  });
+
+  it('leaves a table that may break without the attribute', async () => {
+    const doc: N = { type: 'doc', content: [table({})] };
+    const bytes = await buildOdt(doc, undefined, 'portrait');
+    expect(strFromU8(unzipSync(bytes)['content.xml'])).not.toContain('may-break-between-rows');
+    expect(importOdt(bytes).content.content?.[0]?.attrs?.keepRows ?? null).toBe(null);
+  });
+});