Storage→Spaces, security hardening, production-blocker fixes, tests + CI

Storage
- Migrate document/media storage from local disk to DigitalOcean Spaces (S3);
  lib/storage.ts now streams via the S3 SDK; SPACES_* env vars required.
- Add scripts/migrate-storage-to-spaces.ts (idempotent, one-time).

Security hardening (all report findings)
- DB pool fails closed in production when the CA cert is missing (no more
  silent unverified TLS); warns in dev.
- trustProxy: 1 (was true) so X-Forwarded-For can't be spoofed to evade rate limits.
- Login lockout keyed by (email, ip) so an attacker can't lock out a victim.
- Superadmin auto-grant now requires a verified email.
- CSRF tokens HMAC-signed; exact-path exemptions; logout no longer exempt.
- Upload content-sniffing (magic bytes) rejects spoofed MIME types.
- create-admin.ts reads creds from env/argv; seed-demo.ts guarded behind ALLOW_SEED.

Production-blocker fixes
- SPA deep-link/refresh no longer 500s (decorateReply fix); index.html served no-cache.
- Invoice numbering is transaction-safe (per-firm advisory lock + max sequence),
  eliminating concurrent collisions and delete-reuse — no schema change.
- Checkout guards against double-billing a firm already on a paid plan.
- Fix render-loop in CreateInvoiceDrawer / ManualEntryDrawer (unstable effect deps).

Honesty / trust
- Remove fabricated testimonials, stats, strikethrough "was" prices, contact SLA,
  and the login-panel stats; replace with non-fabricated copy.
- Fix cookie-policy consent-key mismatch. (Legal pages still need lawyer review.)

Quality
- Add Vitest unit tests (file-signature, password hashing) and GitHub Actions CI.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/api/src/routes/billing.ts

@@ -38,6 +38,15 @@ export async function billingRoutes(app: FastifyInstance) {
     const [firm] = await db.select().from(firms).where(eq(firms.id, firmId)).limit(1);
     if (!firm) return reply.code(404).send({ error: 'firm_not_found' });
 
+    // Guard against double-billing: a firm already on a paid plan (or with a live subscription)
+    // must not be able to open a second Checkout session. Send them to the portal instead.
+    if (firm.plan !== 'starter' || firm.stripeSubscriptionId) {
+      return reply.code(409).send({
+        error: 'already_on_paid_plan',
+        hint: 'Manage or change your current plan from the billing portal.',
+      });
+    }
+
     const stripe = getStripe();
 
     // Reuse the customer if we've made one before; otherwise let Checkout create one and we'll