fix(migration): neon() returns rows array directly, not { rows, rowCount }

The pick-a-name B2 migration script (shipped 2026-05-24 in `9abbab6`)
was authored against the @vercel/postgres return shape
`{ rows: [...], rowCount: N }` but uses @neondatabase/serverless's
`neon()` tagged template, which returns the rows array DIRECTLY. As
shipped, the first query at line 37 produced `before === undefined`
and crashed at the `before.length` check on line 44 with
`TypeError: Cannot read properties of undefined (reading 'length')`.

Verified pattern from `lib/database.js` line 33: the wrapper adapter
explicitly checks `Array.isArray(result)` because `neon()` returns
the array directly. AGENTS.md Gotcha #1 mentions @neondatabase and
@vercel/postgres run in parallel; this is exactly the kind of cross-
contamination that creates.

Fix: drop the `{ rows: x }` destructuring in all 3 sites (lines 37,
61, 73) and assign the result directly. Added a 4-line "why" comment
block above the first site so the next person to write a migration
script doesn't make the same mistake.

Hand-verified post-fix:
- node --check: exit 0
- Live run against prod Neon DB: migrated 3 users (admin id=1, alice
  id=5, bob id=6) from @tcgvault.com → @deckhearth.com. Idempotent
  re-run prints "Nothing to migrate."
- No data loss; the broken first attempt didn't reach the UPDATE
  statement (crashed before line 54), so prod was unchanged.

Operator action satisfied by this fix:
- The `pick-a-name` PR #21 / squash `9abbab6` post-merge operator
  action ("run the migration script before next admin login") is now
  complete in prod. Admin login uses `admin@deckhearth.com`.

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

scripts/migrations/2026-05-24-rename-admin-email.js

@@ -34,7 +34,11 @@ async function main() {
 
   const sql = neon(process.env.POSTGRES_URL);
 
-  const { rows: before } = await sql`
+  // NOTE: @neondatabase/serverless's tagged-template returns the rows array
+  // directly — NOT wrapped in { rows, rowCount } like @vercel/postgres does.
+  // See lib/database.js line 33 for the same finding. Do NOT destructure
+  // `{ rows: x }` from a `neon()` result; assign the result directly.
+  const before = await sql`
     SELECT id, email, role
     FROM users
     WHERE email LIKE '%@tcgvault.com'
@@ -58,7 +62,7 @@ async function main() {
     WHERE email LIKE '%@tcgvault.com'
   `;
 
-  const { rows: after } = await sql`
+  const after = await sql`
     SELECT id, email, role
     FROM users
     WHERE email LIKE '%@deckhearth.com'
@@ -70,7 +74,7 @@ async function main() {
     console.log(`  id=${r.id}  role=${r.role}  email=${r.email}`);
   }
 
-  const { rows: stragglers } = await sql`
+  const stragglers = await sql`
     SELECT COUNT(*)::int AS count FROM users WHERE email LIKE '%@tcgvault.com'
   `;
   if (stragglers[0].count !== 0) {