copy(landing): add hero price anchor + primary CTA to $20 signup

- Insert hero-price-anchor under hero-sub: "OSS collects. Platform understands. $20 / seat / month."
- Primary CTA: "Join the waitlist" -> "Start for $20 / seat" -> platform.context-mode.com/signup
- Secondary CTA: "See the personas" -> "Or join the waitlist for hand-onboarding"
- New .hero-price-anchor CSS using existing --accent-light / --accent-dark / --mono vars

Per PRD §4.2. Waitlist demoted to secondary path for hand-onboarding orgs.

web/index.html

@@ -117,6 +117,8 @@ pre code{overflow-wrap:normal;word-break:normal;white-space:pre}
 .hero-product-tag{font-size:13px;color:var(--text-4);margin-bottom:24px;letter-spacing:.04em}
 .hero-product-tag a{color:var(--text-3)}
 .hero-sub{font-size:clamp(1.1rem,2.5vw,1.45rem);color:var(--text-2);font-weight:300;margin-top:18px;max-width:780px;line-height:1.55}
+.hero-price-anchor{font-family:var(--mono);font-size:14px;color:var(--text-2);margin-top:24px;letter-spacing:.01em;padding:10px 16px;background:var(--accent-light);border-radius:6px;display:inline-block}
+.hero-price-anchor strong{color:var(--accent-dark);font-weight:700}
 .hero-stats{display:flex;flex-wrap:wrap;gap:36px;margin-top:44px;padding-top:32px;border-top:1px solid var(--border-light)}
 .hero-stat{min-width:80px}
 .hero-stat .val{font-family:var(--mono);font-size:26px;font-weight:600;color:var(--text);line-height:1}
@@ -393,10 +395,11 @@ footer{padding:64px 0 40px;text-align:center;background:var(--bg-alt);border-top
     <p class="hero-product-tag">the first Solution from <a href="/">Context Mode Platform</a> · for enterprise AI engineering</p>
     <h1 class="h1">Insights — measure the engineering signal your AI tools are actually shipping.</h1>
     <p class="hero-sub">Role-aware observability for Claude Code, Cursor, Copilot, Codex, Gemini, and 10 more AI assistants. 220 patterns. 13 MCP tools. Privacy-first. Sits on top of the open-source plugin <strong>250,000+ developers already trust</strong>.</p>
+    <p class="hero-price-anchor">OSS collects. Platform understands. <strong>$20 / seat / month.</strong></p>
 
     <div class="hero-cta">
-      <a href="#waitlist" class="cta pri">Join the waitlist →</a>
-      <a href="#scenarios" class="cta sec">See the personas</a>
+      <a href="https://platform.context-mode.com/signup" class="cta pri">Start for $20 / seat →</a>
+      <a href="#waitlist" class="cta sec">Or join the waitlist for hand-onboarding</a>
     </div>
 
     <div class="hero-tags">