feat(01-04): Playwright capture toolchain + DSGN-02 approval gallery (D-14, D-12)

- screenshot.mjs: committed real-browser capture tool — tiny node static
  server (theme/ docroot), sheet fullPage capture (390px), 4 mockup captures
  via file:// (network CDN renders; committed screen.png fallback on failure —
  mockups never edited, D-06), basemap capture gated on the proof page's
  RAMS-BASEMAP-READY console signal + 2s tile settle (1280x800); blank gate
  >=10KB per capture; wired as root+theme `capture`
- gallery.html: the DSGN-02 mechanism template — 4 mockup-vs-sheet comparison
  rows + basemap direction row + token ledger (13 typography specimens + 6 hero
  color swatches, names only per D-07) + approval scope strip; CDN-free, built
  from dist/rams.css + var()-only page shell; every later UI phase extends
  this same page
- audit.mjs: gallery.html registered as an implementation page — audit
  covers its <style> block + style attributes + class harvest (354
  declarations, still 0 off-token)
- verified: CAPTURE OK 6/6 (45KB-1.2MB), gallery render check 0 failed
  requests / all 6 images decode, AUDIT CLEAN

theme/package.json

@@ -15,6 +15,7 @@
     "basemap": "node basemap/build.mjs",
     "basemap:preview": "python3 -m http.server 8123",
     "audit": "node ./scripts/audit.mjs ./dist/rams.css",
+    "capture": "node ./scripts/screenshot.mjs",
     "test": "node ./scripts/audit.test.mjs"
   }
 }