plan: intake to plan by a model; doors, labelled groups, the whole card

Work from another session, committed as found (tests green):

- `plan` reads an intake into a plan.yaml (a model decides needs,
  stages, forms and budgets; a person reads the result before build).
- Plans gain `doors` (a first question before the forms, when a front
  door would carry more than five needs), `groups` with labels that a
  select may draw its options from (`options_from: groups`), `private`
  fields kept off public pages, `multiple` selects, and `max_fields`
  as what the intake said the person will tolerate.
- `card.rs`: an alternative as the visitor meets it, in text, so the
  answering visitor and `rate` read the served card, not the heading.
- `rate` reads followup pages from the repo and reports "what happens
  next" as not measured rather than zero when it cannot.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L4jrCgLiKKHAEFuZUJjckH

skill/SKILL.md

@@ -16,13 +16,22 @@ the structure meets every need in `<repo>/needs.yaml`.
 
 ## The order of work
 
+The short path, when a business has filled in an intake: `plan`
+reads it into a `plan.yaml` (a model decides needs, stages, forms and
+budgets; a person reads the result), `build` turns the plan into every
+file of the site with no model deciding anything, and a model writes
+only the words. See the repo README. The steps below are the same
+procedure done by hand, and what to do when the numbers come back.
+
 1. **Interview, then write `needs.yaml` first.** Never pages first.
    Ask who comes to the business and what each of them wants, who in
    the business handles it, and what "handled" means - the states a
    case ends in. Ask what it costs the visitor to ask: how many
-   submissions, how many required fields they will tolerate. If the
-   business is in a sector under `sectors/`, start from that file and
-   cut it down with them; do not start blank.
+   submissions, how many required fields they will tolerate. That
+   number is `max_fields`, and it comes from the person, never from
+   counting the form you would like to write. If the business is in a
+   sector under `sectors/`, start from that file and cut it down with
+   them; do not start blank.
 2. **Write personas in the visitor's words, not the business's.** Two
    or three per need, including one who would not use the trade's own
    vocabulary. Never reuse a phrase you intend to put on a page - a