convoy: scope drop-public-setup (P0 #3 — admin credentials in seed)

Closes P0 #3 from .convoys/ship-readiness.md. Removes the hardcoded
admin@tcgvault.com / admin123 credentials from scripts/setup-neon-db.js
(make it env-var-driven) and from README.md.

Single PR; small surface (2 files). No UI, no API, no migration. Auditor
cohort skipped (no UX/a11y/design-system surface).

P0 #3's third file (pages/api/setup-database.js) was already deleted by
fix-auth-bypass Brief 3.

Architect to address:
  - Existing-admin rotation story (going-forward fix vs. forced reset)
  - Confirm scripts/setup-neon-db.js no-go-zones rule applies to schema
    changes only (this is operational)
  - Whether to add vitest coverage for the env-var-required path

depends_on: bump-next-js (shipped), fix-auth-bypass (shipped)

Co-authored-by: Cursor <cursoragent@cursor.com>

.convoys/drop-public-setup.md

@@ -0,0 +1,88 @@
+---
+name: drop-public-setup
+classification: convoy
+success_metric: |
+  No hardcoded admin credentials in repo (source or README). setup-neon-db.js
+  requires ADMIN_INITIAL_PASSWORD env var. New env-var setup documented in
+  README. Existing deployed admin user (if hash matches the known-weak default)
+  is either rotated or flagged for manual rotation.
+skip:
+  - role-design-system-auditor
+  - role-a11y-auditor
+  - role-ux-reviewer
+  - role-ia-architect
+  - browser-smoke
+status: open
+created: 2026-05-23
+parent: ship-readiness
+addresses: P0 #3
+depends_on:
+  - bump-next-js (shipped)
+  - fix-auth-bypass (shipped — already removed pages/api/setup-database.js)
+---
+
+# Drop public setup
+
+Close P0 #3 from `.convoys/ship-readiness.md`: remove the hardcoded admin
+credentials (`admin@tcgvault.com` / `admin123`) from the seed script and
+the README.
+
+## Scope (verbatim from ship-readiness P0 #3)
+
+- **`scripts/setup-neon-db.js` lines 130-138** — currently creates the admin
+  user with a hardcoded `admin123` bcrypt hash. Change to require an
+  `ADMIN_INITIAL_PASSWORD` env var with no default. Fail loudly (exit
+  non-zero with a clear message) if the env var is unset.
+- **`README.md`** — strip the "Default Admin Account" section. Replace
+  with "run `npm run setup-db` and follow the prompt" (or however the
+  architect decides to phrase it; the spec is "no credentials in README").
+- **`pages/api/setup-database.js`** — already deleted by fix-auth-bypass
+  Brief 3 (commit fc0dd73). Not in scope here; just noting for completeness.
+
+## Out of scope
+
+- Migration tooling (`migration-tool` convoy, P1 #11)
+- Renaming the admin email from `admin@tcgvault.com` to anything else
+  (branding decision belongs to `pick-a-name` convoy, P1 #12)
+- Any other `scripts/seed-*.js` or `scripts/add-*.js` files (those are
+  one-off historical jobs per no-go-zones)
+- Any change to `pages/api/auth/*.js` (fix-auth-bypass shipped; further
+  hardening lives in `cors-tighten` / `add-rate-limiting`)
+
+## Architect's questions
+
+1. **Existing-admin story.** If a deployed environment already has the
+   admin row with `bcrypt.hash('admin123', ...)`, this convoy alone
+   does NOT rotate that password — it only prevents the weak default
+   on *new* envs. Options:
+   a. Going-forward only. Flag for manual rotation; assume any
+      environment with the default already needs operator attention.
+   b. Add a one-time idempotent script under `scripts/migrations/`
+      that checks the admin row's password_hash against the known
+      weak default and forces a reset / requires `ADMIN_RESET_PASSWORD`
+      env var.
+   c. Add a startup check to the deploy pipeline that fails the
+      deploy if the admin row matches the weak hash.
+
+   Recommend the architect pick (a) for simplicity and queue (b) as
+   a follow-up if needed. (a) is consistent with how Brief 1 of
+   fix-auth-bypass handled the JWT_SECRET — going-forward fix-loud,
+   not a sweep of existing data.
+
+2. **`setup-neon-db.js` no-go-zones rule.** The rule says "do NOT
+   edit `scripts/setup-neon-db.js` in place — it's idempotent and
+   meant for first-time setup only." That rule is about *schema*
+   changes (adding columns, etc.). This convoy edits the script's
+   admin-creation logic to add an env-var gate — operational, not
+   schema. Architect should confirm this reading and document the
+   distinction in the brief.
+
+3. **Test coverage.** Brief 5 of fix-auth-bypass introduced vitest.
+   Does this convoy add tests for the env-var-required path? Probably
+   not (setup scripts are typically tested via manual smoke, not unit
+   tests). Architect decides.
+
+## Expected size
+
+1-2 briefs, ~3 files total, no UI, no API surface, no migration. Should
+ship as a single PR (no fan-out).