Rename the Export stage to Finish

It now holds files, sharing, handouts, slides, importing notes, schedule,
co-teachers and earlier versions, not just exports.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/test/App.home.test.jsx

@@ -190,16 +190,16 @@ describe('Home page', () => {
 });
 
 // ---------------------------------------------------------------------------
-// Export stage (useShareLink) and the shared read-only view
+// Finish stage (useShareLink) and the shared read-only view
 // ---------------------------------------------------------------------------
 describe('Project header and sharing', () => {
   const json = (status, data) => Promise.resolve({ ok: status < 400, status, json: () => Promise.resolve(data) });
 
-  test('Export stage → Markdown downloads a file', async () => {
+  test('Finish stage → Markdown downloads a file', async () => {
     const user = await loadChapter();
     addChunk('Paul, a servant', 'Paul, a servant');
     await screen.findByText('1 created');
-    await user.click(screen.getByRole('button', { name: /^export$/i }));
+    await user.click(screen.getByRole('button', { name: /^finish$/i }));
     await user.click(await screen.findByRole('button', { name: /export markdown/i }));
     expect(URL.createObjectURL).toHaveBeenCalled();
   });
@@ -216,7 +216,7 @@ describe('Project header and sharing', () => {
     const user = await loadChapter();
     addChunk('Paul, a servant', 'Paul, a servant');
     await screen.findByText('1 created');
-    await user.click(screen.getByRole('button', { name: /^export$/i }));
+    await user.click(screen.getByRole('button', { name: /^finish$/i }));
     await user.click(await screen.findByRole('button', { name: /enable sharing/i }));
     expect(await screen.findByDisplayValue(/\?share=tok123$/)).toBeInTheDocument();
   });
@@ -310,12 +310,12 @@ describe('Chunk builder', () => {
 });
 
 // ---------------------------------------------------------------------------
-// Stage bar (Chunks / Study / Outline / Script / Export)
+// Stage bar (Chunks / Study / Outline / Script / Finish)
 // ---------------------------------------------------------------------------
 describe('Stage bar', () => {
   test('later stages are disabled until a chunk exists', async () => {
     await loadChapter();
-    for (const name of [/^study$/i, /^outline$/i, /^script$/i, /^export$/i]) {
+    for (const name of [/^study$/i, /^outline$/i, /^script$/i, /^finish$/i]) {
       expect(screen.getByRole('button', { name })).toBeDisabled();
     }
     expect(screen.getByRole('button', { name: /^chunks$/i })).not.toBeDisabled();

src/test/App.pages.test.jsx

@@ -26,7 +26,7 @@ describe('Back to the dashboard', () => {
     await dashboard();
   });
 
-  test.each(['Chunks', 'Study', 'Outline', 'Script', 'Export'])('the %s stage of a study', async (stage) => {
+  test.each(['Chunks', 'Study', 'Outline', 'Script', 'Finish'])('the %s stage of a study', async (stage) => {
     const u = await loadChapter();
     addChunk('Paul, a servant', 'In hope of eternal');
     await screen.findByText('1 created');