docs: turn the accepted panel design into an enforceable contract

panel-redesign.md is rewritten for the accepted direction: three layers
(Bulma as shipped, adapters, own sp- components), the page layouts, what
an implementer must not do, and how that is enforced — guard tests that
land before any template, a design-first CI step, and acceptance by
evidence (test output plus a screenshot of every page beside its mockup,
reviewed by a model that did not write the step).

A components page shows every building block in every state; a screen
may be built from nothing else. panel/check.py lints the mockups against
the contract (class vocabulary, CSS bans on !important, id and page
selectors and stray widths, page structure) and writes
panel/outlines.json, the per-screen component skeleton an implementation
is compared with, so a different design cannot pass as this one.

Own modifier classes now carry the sp- prefix (sp-warn, sp-fail, sp-big,
sp-danger-zone, ...) so the vocabulary is machine-checkable; the lint
also caught a width set outside the layout in the mockup's own CSS.

Agent rule .cursor/rules/panel-design.mdc; roadmap row and section
updated (0/15, still candidate).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

CHANGELOG.md

@@ -23,6 +23,18 @@ document is not part of the release.
 
 ### Added
 
+- Panel redesign, design contract:
+  [docs/plans/panel-redesign.md](docs/plans/panel-redesign.md) rewritten for
+  the accepted direction — three layers (Bulma as shipped, adapters, own `sp-`
+  components), three page layouts, what an implementer must not do, the guard
+  tests that land before any template, a `design-first` CI step and
+  evidence-based acceptance. A
+  [components page](docs/assets/panel-redesign/panel/components.html) shows
+  every building block in every state; `panel/check.py` lints the mockups
+  against the contract and writes `panel/outlines.json`, the per-screen
+  component skeleton an implementation is compared with. Own modifier classes
+  renamed to carry the `sp-` prefix so the vocabulary is machine-checkable.
+  Agent rule `.cursor/rules/panel-design.mdc`; roadmap row updated (`0/15`).
 - Panel redesign, stage 2: the accepted direction drawn on every screen —
   29 pages under [docs/assets/panel-redesign/panel/](docs/assets/panel-redesign/index.html).
   Direction C (Bulma) is the base, with A's postal signature (postmark verdict,