feat: redesign day picker with expandable calendar, status markers & Playwright E2E testing

- Replace modal calendar with inline expandable calendar widget integrated into the day picker.
- Add status indicator dots (attended/absent/pending) to month calendar grid matching day picker.
- Disable and gray out weekend days in calendar when weekend schedule is turned off.
- Redesign extend bar with integrated handle that aligns with the palette.
- Remove start-to-end timing on Today screen's class time rail, showing only start time.
- Implement Playwright E2E and visual testing suite with multi-screen capture scripts.
- Add cascade DELETE endpoints for subjects and versioned recurring timetable entries.

scripts/take-screenshots.mjs

@@ -0,0 +1,66 @@
+import { chromium } from 'playwright';
+import { mkdirSync } from 'node:fs';
+
+const OUT_DIR = './screenshots';
+mkdirSync(OUT_DIR, { recursive: true });
+
+async function capture() {
+  const browser = await chromium.launch({ headless: true });
+  
+  // iPhone 14 dimensions & scale
+  const context = await browser.newContext({
+    viewport: { width: 390, height: 844 },
+    deviceScaleFactor: 2,
+    isMobile: true,
+    hasTouch: true,
+  });
+
+  const page = await context.newPage();
+
+  console.log('Navigating to Today screen...');
+  await page.goto('http://127.0.0.1:3000/');
+  await page.waitForTimeout(2000);
+  await page.screenshot({ path: `${OUT_DIR}/01-today.png`, fullPage: false });
+
+  console.log('Navigating to Timetable...');
+  const timetableTab = page.locator('text=Timetable');
+  if (await timetableTab.isVisible()) {
+    await timetableTab.click();
+    await page.waitForTimeout(1500);
+    await page.screenshot({ path: `${OUT_DIR}/02-timetable.png`, fullPage: false });
+  }
+
+  console.log('Navigating to Attendance...');
+  const attendanceTab = page.locator('text=Attendance');
+  if (await attendanceTab.isVisible()) {
+    await attendanceTab.click();
+    await page.waitForTimeout(1500);
+    await page.screenshot({ path: `${OUT_DIR}/03-attendance.png`, fullPage: false });
+  }
+
+  console.log('Navigating to Settings...');
+  const settingsTab = page.locator('text=Settings');
+  if (await settingsTab.isVisible()) {
+    await settingsTab.click();
+    await page.waitForTimeout(1500);
+    await page.screenshot({ path: `${OUT_DIR}/04-settings.png`, fullPage: false });
+  }
+
+  console.log('Navigating to Account...');
+  await page.goto('http://127.0.0.1:3000/account');
+  await page.waitForTimeout(1500);
+  await page.screenshot({ path: `${OUT_DIR}/05-account.png`, fullPage: false });
+
+  console.log('Navigating to Onboarding...');
+  await page.goto('http://127.0.0.1:3000/onboarding');
+  await page.waitForTimeout(1500);
+  await page.screenshot({ path: `${OUT_DIR}/06-onboarding.png`, fullPage: false });
+
+  await browser.close();
+  console.log('All screenshots captured in', OUT_DIR);
+}
+
+capture().catch((err) => {
+  console.error(err);
+  process.exit(1);
+});