feat(seo-data,seo,geo): R2 — refuse to score what JS paints; no Playwright

Arbitrated (user): honest refusal on SPA, no headless browser.

STEP 2 has recorded `RENDERING: SSR/SSG/SPA/hybrid` since forever and NOTHING
ever acted on it. (The inventory claimed a "SPA severely limited" §0 flag
compensated — it does not exist. Seventh subagent claim this branch has had to
disprove.) So on a client-rendered site the FULL audit curls an empty shell,
every meta/H1/JSON-LD check reports "missing", and the agent emits a page of
false findings — plus a bundle that would "fix" tags which already exist.

rendercheck reads the verdict from what the server SENT. package.json cannot
tell a React SPA from a Next.js SSR app; the served bytes can. Stdlib only.

The refusal is the point:
- client-rendered → On-page is N/A, excluded from the weighted global, NOT
  scored zero. A zero says "your on-page is bad"; N/A says "we could not see
  it". Only one is true, and /client-handover gates on this number.
- No bundle item may come from a live on-page check on such a site.
- The report still says what IS auditable (robots, sitemap, headers, config,
  CrUX field data — real users, hydration included — GSC, legal, images)
  rather than returning an empty verdict.
- geo refuses Content Shape the same way, and states the sharper fact: AI
  crawlers are WORSE at JS than Googlebot. GPTBot/PerplexityBot/ClaudeBot
  fetch HTML and largely do not execute it, so a client-rendered site is not
  merely unauditable by us — it is near-invisible to the engines this audit
  exists to serve. §0 alert + SSR/SSG as the top user action.

Script/style text is not page text: a React shell with a fat inline
window.__INITIAL_STATE__ measures 7 chars. Without that skip a 200 KB bundle
reads as a rich page — the detector would fail exactly where it matters.

Verified on both extremes, not just the happy path: zenquality 7650 chars/1
h1/9 jsonld and lavageangels356 13973/1/1 → server-rendered, no warning; a
Vite/React shell fixture → client-rendered, 7/0/0, warned.

seo-data 136 -> 144 pass, 0 fail; full suite green; shellcheck + py_compile
clean.

lib/seo-data/seo-data.test.sh

@@ -135,6 +135,22 @@ has "billion-laughs refused"     "$DTD" '"status": "degraded"'
 has "dtd reason is distinct"     "$DTD" 'unsafe_xml_dtd'
 hasnt "dtd never parsed"         "$DTD" '"count"'
 
+echo "── render_check (R2) ──"
+SPA="$(SEO_DATA_MOCK_DIR="$SD/fixtures-spa" python3 "$SD/render_check.py" \
+  --url https://spa.example/)"
+has "spa → client-rendered"      "$SPA" '"verdict": "client-rendered"'
+has "spa has no h1 in html"      "$SPA" '"h1_in_html": 0'
+has "spa warns about false negs" "$SPA" 'false'
+# the shell carries a fat window.__INITIAL_STATE__ script: script text is NOT
+# page text, or a 200KB React bundle would read as a rich page
+has "script text is not content" "$SPA" '"body_text_chars": 7'
+SSR="$(SEO_DATA_MOCK_DIR="$SD/fixtures-ssr" python3 "$SD/render_check.py" \
+  --url https://ssr.example/)"
+has "ssr → server-rendered"      "$SSR" '"verdict": "server-rendered"'
+has "ssr counts jsonld"          "$SSR" '"jsonld_in_html": 1'
+has "ssr sees meta description"  "$SSR" '"meta_description_in_html": true'
+hasnt "ssr emits no warning"     "$SSR" 'warning'
+
 echo "── linkgraph ──"
 LG="$(SEO_DATA_MOCK_DIR="$SD/fixtures-linkgraph" python3 "$SD/linkgraph.py" \
   --url https://ex.com/sitemap.xml)"