feat: add testing infrastructure — Vitest, Playwright, CI, git hooks

Add comprehensive testing covering 420 unit/handler tests across 24 Vitest
files, 9 Playwright E2E specs, accessibility scans, and visual regression.
Includes GitHub Actions CI, Husky pre-push hook, and TESTING.md docs.

e2e/events.spec.js

@@ -0,0 +1,64 @@
+import { test, expect } from '@playwright/test'
+
+test.describe('Events list page', () => {
+  test('events list loads', async ({ page }) => {
+    await page.goto('/events')
+    await expect(page.locator('h1', { hasText: 'Events' })).toBeVisible()
+  })
+
+  test('filter bar has type filters', async ({ page }) => {
+    await page.goto('/events')
+    const filterBar = page.locator('.filter-bar')
+    await expect(filterBar).toBeVisible()
+
+    for (const label of ['All', 'Workshops', 'Community', 'Social', 'Showcase']) {
+      await expect(filterBar.locator('button', { hasText: label })).toBeVisible()
+    }
+  })
+
+  test('past events toggle exists and can be checked', async ({ page }) => {
+    await page.goto('/events')
+    const checkbox = page.locator('input[type="checkbox"]')
+    await expect(checkbox).toBeVisible()
+    await expect(page.locator('text=Show past events')).toBeVisible()
+
+    await checkbox.check()
+    await expect(checkbox).toBeChecked()
+
+    // Page should still render without errors after toggling
+    await expect(page.locator('h1', { hasText: 'Events' })).toBeVisible()
+  })
+
+  test('clicking a filter button activates it', async ({ page }) => {
+    await page.goto('/events')
+    const workshopsBtn = page.locator('.filter-bar button', { hasText: 'Workshops' })
+    await workshopsBtn.click()
+    await expect(workshopsBtn).toHaveClass(/active/)
+  })
+
+  test('event links navigate to detail page', async ({ page }) => {
+    await page.goto('/events')
+
+    // Check the past events toggle so we see all events
+    await page.locator('input[type="checkbox"]').check()
+
+    const eventLinks = page.locator('.event-row a')
+    const count = await eventLinks.count()
+
+    if (count === 0) {
+      // No events in the database — just verify the empty state renders
+      await expect(page.locator('.empty', { hasText: 'No events found' })).toBeVisible()
+      return
+    }
+
+    // Click the first event link and verify navigation
+    const firstLink = eventLinks.first()
+    const href = await firstLink.getAttribute('href')
+    await firstLink.click()
+    await page.waitForURL(/\/events\//)
+
+    expect(page.url()).toContain('/events/')
+    // Detail page should have an h1 with the event title
+    await expect(page.locator('h1')).toBeVisible()
+  })
+})