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/join-flow.spec.js

@@ -0,0 +1,83 @@
+import { test, expect } from '@playwright/test'
+
+test.describe('Join page — member signup flow', () => {
+  test('join form loads with all fields', async ({ page }) => {
+    await page.goto('/join')
+
+    await expect(page.locator('#join-name')).toBeVisible()
+    await expect(page.locator('#join-email')).toBeVisible()
+    await expect(page.locator('#circle-community')).toBeAttached()
+    await expect(page.locator('#circle-founder')).toBeAttached()
+    await expect(page.locator('#circle-practitioner')).toBeAttached()
+    await expect(page.locator('#join-contribution')).toBeVisible()
+    await expect(page.locator('.form-submit')).toBeVisible()
+  })
+
+  test('submit button disabled when form incomplete', async ({ page }) => {
+    await page.goto('/join')
+
+    // Clear name and email — circle defaults to community, contribution defaults to $15
+    await page.locator('#join-name').fill('')
+    await page.locator('#join-email').fill('')
+
+    // Button should be disabled with empty required fields
+    await expect(page.locator('.form-submit')).toBeDisabled()
+
+    // Fill only name — still incomplete
+    await page.locator('#join-name').fill('Test User')
+    await expect(page.locator('.form-submit')).toBeDisabled()
+
+    // Fill email too — now all fields are populated and button should be enabled
+    await page.locator('#join-email').fill('incomplete-test@example.com')
+    await expect(page.locator('.form-submit')).toBeEnabled()
+  })
+
+  test('fill and submit free tier', async ({ page }) => {
+    const uniqueEmail = `test-e2e-${Date.now()}@example.com`
+
+    await page.goto('/join')
+
+    await page.locator('#join-name').fill('E2E Test User')
+    await page.locator('#join-email').fill(uniqueEmail)
+    await page.locator('#circle-community').check({ force: true })
+    await page.locator('#join-contribution').selectOption('0')
+
+    await expect(page.locator('.form-submit')).toBeEnabled()
+    await page.locator('.form-submit').click()
+
+    // Free tier skips payment (step 2) and goes to confirmation (step 3)
+    // or redirects to /welcome. Wait for either outcome.
+    await expect(
+      page.getByText('Welcome to Ghost Guild!').or(page.locator('.success-box'))
+    ).toBeVisible({ timeout: 15000 })
+  })
+
+  test('duplicate email shows error', async ({ page }) => {
+    // First submission — create a member
+    const duplicateEmail = `test-e2e-dup-${Date.now()}@example.com`
+
+    await page.goto('/join')
+    await page.locator('#join-name').fill('Dup Test User')
+    await page.locator('#join-email').fill(duplicateEmail)
+    await page.locator('#circle-community').check({ force: true })
+    await page.locator('#join-contribution').selectOption('0')
+    await page.locator('.form-submit').click()
+
+    // Wait for first submission to succeed
+    await expect(
+      page.getByText('Welcome to Ghost Guild!').or(page.locator('.success-box'))
+    ).toBeVisible({ timeout: 15000 })
+
+    // Navigate back and try to register the same email again
+    await page.goto('/join')
+    await page.locator('#join-name').fill('Dup Test User Again')
+    await page.locator('#join-email').fill(duplicateEmail)
+    await page.locator('#circle-community').check({ force: true })
+    await page.locator('#join-contribution').selectOption('0')
+    await page.locator('.form-submit').click()
+
+    // Should show an error about the email already existing
+    await expect(page.locator('.error-box')).toBeVisible({ timeout: 10000 })
+    await expect(page.locator('.error-box')).toContainText(/already/i)
+  })
+})