fix(seo,geo): I5 — disclose sampling coverage instead of implying an audit

Both agents sample (seo-analyzer.md:403 "sample 5-15 key pages",
geo-analyzer.md:460 "Sample 5-10 key pages") and neither states it. The
report says "audit". On a 500-page site a 12-page sample is 2.4%, and the
reader cannot know that unless it is printed. /client-handover gates on
these scores.

The denominator was already within reach: STEP 4 fetches sitemap.xml. Count
its URLs and the coverage ratio is free — same data C1 will use for
sitemap-driven crawl later.

- Mandatory COVERAGE line in both scoring blocks: N of M sitemap URLs (P%),
  or "total UNKNOWN" when no sitemap. Never omitted, never rounded up.
- seo: <25% coverage repeats in §0 as a major alert. Sample by risk (one
  page per template + GSC position 4-10 quick wins), name skipped templates
  — an un-sampled template is an un-audited template.
- geo: scoped honestly rather than blanket — COVERAGE bounds the per-page
  axes (Content Shape, page-level Schema.org) but NOT the site-wide ones
  (AI Crawlers Policy, llms.txt are single files, fully read). One ratio
  should not discredit axes it does not govern.

Verified: make test 35 GREEN / 0 RED.

agents/seo-analyzer.md

@@ -400,8 +400,22 @@ Fetch rendered HTML. Extract and analyze:
 
 ## STEP 5 — ON-PAGE AUDIT `[both]`
 
+**Record the denominator BEFORE sampling.** This step samples; the report
+says "audit". Count the URLs in `sitemap.xml` (fetch it in full — the
+`head -50` in STEP 4 is a preview, not a count). That count is the coverage
+denominator, and it feeds the mandatory COVERAGE line in STEP 9. No sitemap
+→ denominator unknown: say so, never let silence imply full coverage. On a
+500-page site a 12-page sample is 2.4% — the On-page score is an
+extrapolation from it, and the reader cannot know that unless you print it.
+
 ### Meta tags per page (sample 5-15 key pages)
 
+Sample by risk, not convenience: homepage + top templates (one per page
+type: service, city, blog, product, legal) + any page GSC flags as a
+position 4-10 quick win. Same template audited twice buys nothing; an
+un-sampled template is an un-audited template — name the templates you
+skipped.
+
 For each sampled page:
 ```
 PAGE: <path>
@@ -738,6 +752,8 @@ misroutes the client-handover gate and the user's effort.
 
 ```
 SEO SCORING (<depth>)
+COVERAGE       : <N> of <M> sitemap URLs (<P>%) — templates skipped: <list|none>
+                 | <N> pages, total UNKNOWN (no sitemap)
 Technical      : XX/20  <justification>
 On-page        : XX/20  <justification>
 SEO Local      : XX/20 | N/A
@@ -749,6 +765,12 @@ Legal          : XX/20  <justification>
 SEO GLOBAL (weighted): XX.X/20 (<depth>)
 ```
 
+**COVERAGE is mandatory, never omitted, never rounded up.** It is the
+honesty bound on every page-level axis: On-page and the on-page share of
+Technical are extrapolations from the sample. If coverage < 25%, repeat it
+in §0 as a major alert — a 17/20 drawn from 3% of a site is not a 17/20, and
+`/client-handover` gates on these numbers.
+
 Per user instruction: this score represents **80% of the combined
 final score for local B2C (20% for GEO), or 75% for SaaS/national
 (25% for GEO)**. The `/seo` dispatcher combines SEO and GEO scores.