fix: harden Firebase auth error handling and fix silent regression in RegisterPage

[AlexLopezGomez]

Summary

• Fixed silent failure where social auth errors on RegisterPage Step 1 were invisible to the user (error was rendered only on Step 3; navigating away cleared it). Caught by Codex adversarial review during CEO+Eng review session.
• SocialAuth now owns its own error display via local state, calls clearError() after catching to prevent parent forms (SignInForm, SignUpFlow) from double-displaying the same error message.
• Updated auth/popup-closed-by-user message to mention missing env vars and Firebase Authorized Domains as the most common cause on fresh deployments (matching CLAUDE.md runbook).
• Error color in SocialAuth unified to text-verdict-fail design system token (was text-red-500).
• firebaseConfigured export added to firebase.js — UI renders "Social sign-in is not configured." when Firebase env vars are absent.
• Named error handling for auth/account-exists-with-different-credential, auth/popup-blocked, auth/popup-closed-by-user, auth/unauthorized-domain.
• Meta tag fallback for Firebase config enables Docker runtime injection as alternative to build-time env vars.
• CLAUDE.md: Docker base image rules, npm install vs npm ci, Firebase auth deployment checklist and error code reference.
• TODOS.md: created with P2 items for Firebase health endpoint and Vitest auth unit tests.

Test Coverage

Test generation skipped — no test framework configured. Vitest setup tracked in TODOS.md (P2).

Test plan written to ~/.gstack/projects/Quorum/ for /qa and /qa-only consumption.

Critical paths to verify manually:

• Google OAuth: click → popup → auth → redirect to /app
• GitHub OAuth: same
• Social auth failure on RegisterPage Step 1: error must appear on Step 1, not hidden until Step 3
• Social auth failure in SignInForm: error shown once (inside SocialAuth), not twice
• Firebase env vars absent: "Social sign-in is not configured." shown, no buttons

Pre-Landing Review

1 issue found, 1 auto-fixed:

• [AUTO-FIXED] SocialAuth.jsx:50 — text-red-500 → text-verdict-fail (design system consistency)

Design Review

Design Review (lite): 1 finding — 1 auto-fixed, 0 skipped. Color token consistency: clean.

Eval Results

No prompt-related files changed — evals skipped.

Greptile Review

No Greptile comments.

TODOS

• TODOS.md created with 2 new P2 items:
  • Firebase auth health endpoint (GET /api/auth/firebase-health)
  • Vitest + React Testing Library auth unit tests

Test plan

• Google sign-in on /login
• GitHub sign-in on /login
• Social auth failure on /register Step 1 shows error in Step 1
• Social auth failure in sign-in form shows error once (not twice)
• Deploy without VITE_FIREBASE_* env vars shows "not configured" message

🤖 Generated with Claude Code