Add product marketing context (week 1 enabler)

Hypothesis: every later copy decision (title/meta rewrites, hosting hub,
CTA blocks) will be written against a single grounded source of truth —
real ICP from GSC query data, verified host prices, and an explicit
never-use list for the site's fabricated proof — instead of being
improvised per page. Metric: none (enabler); success is that week 2's
proof-removal and week 3's CTR rewrites stop inventing claims.

Also stop serving internal strategy publicly: .agents/ and growth/ are
added to .vercelignore (.md was listed but growth/PLAN.md still returns
200 live).

.vercelignore

@@ -31,6 +31,12 @@ pages-status.json
 validation-report.md
 missing-keywords*.md
 
+# Exclude internal strategy (must never be publicly served)
+.agents/
+.agents/**
+growth/
+growth/**
+
 # Exclude OS files
 .DS_Store
 Thumbs.db