chore: replace hardcoded version badge with dynamic Shields.io release badge

The hero section now shows the actual latest release version via a
Shields.io badge linked to GitHub Releases — zero JS, auto-updating.

Author: molty3000

docs/index.html

@@ -18,7 +18,7 @@
   <meta name="twitter:description" content="The fastest, minimal Go autonomous agent runtime. ~12 MB static binary, zero frameworks.">
   <meta name="keywords" content="Go, autonomous agent, AI agent, LLM, ReAct, MCP, parallel execution, interaction modes, Telegram bot, Docker sandbox, CLI, benchmark, open-source">
   <meta name="robots" content="index, follow">
-  <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline' https://assets.21no.de; font-src https://assets.21no.de; img-src 'self' https://21no.de; connect-src 'self'">
+  <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline' https://assets.21no.de; font-src https://assets.21no.de; img-src 'self' https://21no.de https://img.shields.io; connect-src 'self'">
   <link rel="icon" type="image/x-icon" href="https://21no.de/logo-v2.png">
   <link rel="apple-touch-icon" href="https://21no.de/logo-v2.png">
   <link rel="stylesheet" href="https://assets.21no.de/fonts/fonts.css">
@@ -320,7 +320,7 @@
   <div class="container">
     <h1>odek</h1>
     <p class="sub"><span class="size">~12 MB</span> static binary · Zero frameworks.<br>Think, therefore act.</p>
-    <div class="badge" style="margin-top:12px;display:inline-block;background:var(--accent-subtle);border:1px solid rgba(56,189,248,.15);border-radius:6px;padding:5px 12px;font-size:0.8125rem;font-family:var(--font-mono);color:var(--accent);">v0.48.0</div>
+    <a href="https://github.com/BackendStack21/odek/releases" target="_blank" style="margin-top:12px;display:inline-block;"><img src="https://img.shields.io/github/v/release/BackendStack21/odek?style=flat&label=&color=38bdf8&labelColor=0a1628" alt="Latest release" style="height:28px;border-radius:6px;"></a>
 
     <div class="install-block">
       <code>go install github.com/BackendStack21/odek/cmd/odek@latest</code>