fix(design): run the DOM dump in the page on both engines; align doctrine with the catalog

The DOM-dump script is an arrow function, not a self-calling IIFE: Aside's
`pg.evaluate($_DUMP)` receives the function and runs it in the page (the IIFE
form executed in the repl sandbox, where `document` does not exist), and the
fallback engine calls it with `$B js "($_DUMP)()" --out --raw`. Hygiene widens
to every URL-bearing attribute (src, srcset per candidate, poster, action,
formaction, data, ping, cite lose their query strings and fragments) and to
data: URLs inside existing <style> nodes. The persist and scan blocks restate
REPORT_DIR and RUN_ID literally instead of relying on a shell variable from an
earlier block; the baseline's targetSet is defined per mode (repo-relative
paths in source mode, page slugs in DOM mode) so DOM-mode deltas can match; the
PR-body Detector line lists the states the probe can actually print. The DOM
fixture is re-captured with the new script from outside the repo (the engine
walks up from cwd for DESIGN.md, which the metadata now records).

Doctrine contradictions the design specialist found: the landing-page motion
rule matches the one-authored-moment reflex; the background rule names the
catalog's halo/spotlight/stripe/grid slop instead of asking for gradients; the
universal font rule is scoped to the display voice with the body/UI exceptions;
"two typefaces max" allows the mono; the methodology's banned-font line renders
BANNED_FONTS; Courier New is banned outright; the Brutalist, Retro-Futuristic,
and Playful menu entries stop recommending system stacks, glow, and bounce; the
coherence nudge uses the decoration vocabulary; Path A's gate names the display
voice; font-loading prose points at the source the procedure verified;
centered-everything is MEDIUM (an aggregate heuristic); the mockup guard reads
"Never by default (unless the brief above asks for it)". The checklist's
AUTO-FIX list renders the catalog's auto-fix rules; category 9 and the Hard
Rules pointer count from the same partition helpers (detectorSlopEntries,
judgmentTellEntries); the handoff list renders from HANDOFF_COMMANDS; a missing
catalog id fails gen-skill-docs by name. gstack's own DESIGN.md gains border
tokens and Decisions Log rows for its live-feed pulse and 11px mono labels.
frontend-scope is case-sensitive like the bash arm. gen-skill-docs shares one
emitGenerated helper for sections and lib-derived assets; renderCatalog keeps
the one style with a caller. Tests: shared sliceBetween that fails on a missing
end marker, the slop-gate fixture's real end marker, an isolated browse daemon
for the DOM-mode E2E, the DOM hygiene test gated to CI or opt-in, docs notes
for the two superseded plan sentences.

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

test/helpers/skill-fixture.ts

@@ -250,3 +250,16 @@ export function extractSkillHead(skillDir: string, bodyLineCount = 30): string {
   const head = bodyLines.slice(0, bodyLineCount).join('\n').trimEnd();
   return `${frontmatter}\n${head}\n\n<!-- body truncated by test/helpers/skill-fixture.ts — routing fixture needs frontmatter only -->\n`;
 }
+
+/**
+ * Slice a rendered skill between two literal markers. Both must exist: a
+ * missing END marker would silently hand the agent the rest of the file, which
+ * is exactly the "copied the whole SKILL.md" failure the E2E fixtures avoid.
+ */
+export function sliceBetween(text: string, start: string, end: string): string {
+  const i = text.indexOf(start);
+  if (i < 0) throw new Error(`skill fixture: start marker not found: ${start}`);
+  const j = text.indexOf(end, i + start.length);
+  if (j < 0) throw new Error(`skill fixture: end marker not found after start: ${end}`);
+  return text.slice(i, j);
+}