web: themeable auth pages via shared shell + config hooksVerified

The server-rendered pages (login, TOTP, password reset, email verification)
each built their own bare <!doctype>...<body> with no CSS hook, so an
embedding app could not brand them — they rendered as unstyled Times New
Roman forms regardless of the host's design.

Add a single RENDER-AUTH-PAGE shell that all seven emitters share, driven by
three optional config keys:
  :brand      product name in <title>          (default "Usher")
  :head-html  raw markup injected into <head>   (e.g. a stylesheet <link>)
  :body-class extra class on <body>
The markup now carries stable usher-* class hooks (usher-card, usher-title,
usher-form, usher-field, usher-input, usher-submit, usher-social, ...) so a
host stylesheet themes the pages without Usher owning their visual design.
All three keys default to nil/"Usher", so existing output is unchanged.

Also: real <label>s instead of placeholder-as-label, and autocomplete hints
(username/current-password/new-password/one-time-code) on the inputs.

http-smoke gains GET /authorize assertions for the brand title, head-html
injection, body-class, and usher-* form classes. make test: 199/199;
http-smoke: 15/15.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Anthony Green2026-06-30 07:51:43 -0400 843b934df78e9613084bbd4dc77f6dab94f5aa06
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>