Add Playwright tests for block folding functionality

- Test that fold gutter doesn't lose editor focus when clicked
- Test that line number gutter doesn't lose editor focus when clicked

tests/folding.spec.js

@@ -0,0 +1,68 @@
+import { test, expect } from "@playwright/test";
+import { HeynotePage } from "./test-utils.js";
+
+let heynotePage
+
+test.beforeEach(async ({ page }) => {
+    heynotePage = new HeynotePage(page)
+    await heynotePage.goto()
+});
+
+test.describe("Block Folding", () => {
+    test.beforeEach(async ({ page }) => {
+        // Set up test content with multiple blocks
+        await heynotePage.setContent(`
+∞∞∞text
+Block A
+Line 2 of Block A
+Line 3 of Block A
+∞∞∞javascript
+console.log("Block B")
+let x = 42
+return x * 2
+∞∞∞text
+Block C
+Single line block
+∞∞∞markdown
+# Block D
+This is a markdown block
+- Item 1
+- Item 2
+`)
+        //await page.waitForTimeout(100);
+        expect((await heynotePage.getBlocks()).length).toBe(4)
+    });
+
+    test("fold gutter doesn't lose editor focus when clicked", async ({ page }) => {
+        // Position cursor in first block
+        await heynotePage.setCursorPosition(20) // Middle of Block A
+        
+        // Click on fold gutter to fold the block
+        await page.locator(".cm-foldGutter").first().click()
+        await page.waitForTimeout(100)
+        
+        // Type a character - this should work if editor maintained focus
+        await page.locator("body").pressSequentially("xyz yay")
+        //await page.waitForTimeout(100)
+        
+        // Verify the character was added to the buffer
+        const content = await heynotePage.getContent()
+        expect(content).toContain("xyz yay")
+    });
+
+    test("line number gutter doesn't lose editor focus when clicked", async ({ page }) => {
+        // Position cursor in first block
+        await heynotePage.setCursorPosition(20) // Middle of Block A
+        
+        // Click on line number gutter
+        await page.locator(".cm-lineNumbers .cm-gutterElement:visible").first().click()
+        await page.waitForTimeout(100)
+        
+        // Type a character - this should work if editor maintained focus
+        await page.locator("body").pressSequentially("abc test")
+        
+        // Verify the character was added to the buffer
+        const content = await heynotePage.getContent()
+        expect(content).toContain("abc test")
+    });
+});