Detector: add italic-serif display headline + hero eyebrow chip rules (#127) (#129)

* feat(detector): flag italic-serif display heroes and uppercase eyebrow chips (#127)

Two new rules covering the structural tells of late-2025/early-2026
AI-generated marketing pages.

- italic-serif-display: oversized italic serif (Fraunces, Recoleta,
  Newsreader, Playfair, Cormorant, Tiempos, ...) as the primary hero
  headline. Anchored on h1 (or h2 at >= 48px) with font-style: italic
  and a serif primary face.
- hero-eyebrow-chip: uppercase letter-spaced label sitting as the
  previousElementSibling of a hero h1 (font-size >= 48px). Bounded
  text length 2-30 chars, letter-spacing >= 1.6px, font-size <= 14px.
  The pill-chip variant (background + border-radius: 999px) falls out
  of the same gates for free.

Both follow the existing icon-tile-stack pattern: pure check function +
browser DOM adapter + jsdom adapter, wired into both element loops.
Two-column fixtures (4 flag / 6 pass each) drive the jsdom tests.

Skill copy in source/skills/impeccable/reference/typography.md and
critique.md calls out the patterns by name. The italic-serif rule's
description acknowledges that editorial/magazine register may legitimately
want the pattern -- judge by context.

Closes #127

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* Add sandbox gotchas for Codex

* Trim verbose detector skill copy

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: Paul Bakaus <paulbakaus@pauls-mbp-3.lan>

.github/skills/impeccable/reference/critique.md

@@ -39,7 +39,7 @@ Return structured findings covering: AI slop verdict, heuristic scores, cognitiv
 
 #### Assessment B: Automated Detection
 
-Run the bundled deterministic detector, which flags 25 specific patterns (AI slop tells + general design quality).
+Run the bundled deterministic detector, which flags 27 specific patterns (AI slop tells + general design quality).
 
 **CLI scan**:
 ```bash