Land FW-601, FW-602, FW-603 on preview (with billing) - #47

Accounts kept only an email address, so the header could only show
that. Now an account can have a name:

- api: migration 0003 adds users.name, and the user the service
  describes carries it (null until given). /auth/verify takes an
  optional name, which names a new account or one without a name yet,
  and never replaces one. A new POST /auth/profile sets or clears it
  for the signed-in account. A name is trimmed, its runs of spaces made
  one, and up to 80 characters; control characters and bidirectional
  overrides are refused, before the code is tried, so a bad name
  doesn't use up a try. The admin listing carries names too.
- site: /signup asks for an optional name above the address. /account
  has a Name field to change or clear it. The header shows the name,
  with the initials of its first and last words ("AL"), and the menu
  shows the name above the address; without a name, both show the
  address as before. The console's footer and the admin page show it
  too. The in-browser demo keeps the name with its session.

Tests: api/test/profile.test.mjs covers giving, keeping, changing and
clearing a name, what's refused, the session and origin checks, and
the admin listing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pillOutline sits on shadcn's default Button variant, whose
hover:bg-primary/80 it never overrode, so under the pointer an
outlined button (Sign out on /account, Resend code and Use another
address while signing in, Save name) turned near-black with its dark
text unreadable. It now keeps its fill, and only its border darkens,
as intended.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

The service's SIGNUP_MODE is now "open", so whoever signs in uses the
console, and accounts that were waiting are let in too. The waitlist
stays in the code: setting it back to "waitlist" brings it back.

The site stops talking about a waitlist and early access:

- The landing page's last section is Get started (#get-started), with
  "Get started free" for /signup. The header links to it as Sign up
  (as short as Waitlist was, so the links still fit one row at phone
  widths), and the footer as Get started.
- /pricing says to start on Free and that paid plans aren't billed yet.
  The Free, Launch and Scale cards say Get started, and the FAQ says
  you can sign up now.
- /signup's lead says the account opens the console again.
- The admin page opens on All while sign-up is open, since nobody
  waits, and Remove's question no longer says the account goes back on
  the waitlist.

The API tests now follow the deployed setting, and the waitlist tests
turn the waitlist on themselves. api/README.md says sign-up is open
and how to put the waitlist back.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Renumber the profile-name migration to 0004: preview already has
0003_billing.sql, and two 0003 migrations would apply in name order
by accident. Keep both the billing routes and /auth/profile, and show
the Name form above the billing card on /account.

Keep the landing Pricing section, with Get started after it, and both
Pricing and Get started in the header and footer. Drop #43's "paid plans
aren't billed yet" copy: Paygate billing is live, so /pricing now says
to start on Free and upgrade when needed. The billing suite pins
SIGNUP_MODE to waitlist, since its waiting-account case relied on the
old deployed default. Rebuild docs/.