test: E2E browser tests for login + signup (Task 18)

docs/superpowers/e2e/signup-flow.md

@@ -0,0 +1,25 @@
+# E2E Test: Web Signup Flow
+
+**App URL:** https://localhost:3000
+**Date:** 2026-05-27
+
+## Results
+- [x] Signup page loads without console errors
+- [x] "Create your account" heading is present
+- [x] Name, email, and password fields are present
+- [x] Social login buttons render
+- [x] Proxy guard works: `/signup?step=otp` redirects to `/signup` for unauthenticated users
+- [ ] Full signup — requires OTP verification (manual test needed)
+
+## Test Steps (agent_browser)
+1. ✅ Open https://localhost:3000/signup
+2. ✅ Snapshot — "Create your account" heading (ref=e2), name (e5), email (e6), password (e7) fields
+3. ⏳ Fill fields + Create account + OTP verify (requires real email)
+
+## Screenshots
+- `screenshots/signup-flow.png`
+- `screenshots/proxy-guard.png` (redirect from `/signup?step=otp` to `/signup`)
+
+## Notes
+- Proxy guard (Task 5) verified: unauthenticated `?step=otp` → redirect to `/signup`
+- Two-step flow: register → OTP verify (passkey step is deferred)