Storylines: the same site told several ways, one per visitor, counted

Any text a person reads may be a list, one entry per storyline, every
list the same length. A visitor is given one storyline for the whole
site and reads it on every page and in every mail about their case.
Records and events carry the storyline; GET /report gives counts per
bucket, storyline and state, and nothing else.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GT37Z1Xtfd9pUuQtMTg6Yt

docs/content-reference.md

@@ -38,6 +38,11 @@ mail:
 
 `mail.from` is required as soon as any state declares a mail.
 
+Any text a person reads (`name`, `description`, `label`,
+`placeholder`, a mail's `subject` and `body`, `consequence`,
+`encouragements`) may be a list instead of one string: one entry per
+[storyline](storylines.md), all lists the same length.
+
 ## A question
 
 One YAML file is one page.