fix: version strings showed 4.2.0; use CARGO_PKG_VERSION so they never go stale

The REPL banner and HTML-report footer hardcoded v4.2.0 while the crate is 4.2.1.
Both now interpolate env!("CARGO_PKG_VERSION"); web title/sidebar/comments set to
4.2.1. --version already read the crate version.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/public/app.js

@@ -1,5 +1,5 @@
 'use strict';
-/* NeuroSploit v4.2.0 — web console frontend. Vanilla JS, no build step. */
+/* NeuroSploit v4.2.1 — web console frontend. Vanilla JS, no build step. */
 
 const $ = (sel, root = document) => root.querySelector(sel);
 const $$ = (sel, root = document) => Array.from(root.querySelectorAll(sel));

web/public/index.html

@@ -3,7 +3,7 @@
 <head>
 <meta charset="utf-8" />
 <meta name="viewport" content="width=device-width, initial-scale=1" />
-<title>NeuroSploit v4.2.0 — Console</title>
+<title>NeuroSploit v4.2.1 — Console</title>
 <link rel="icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🧠</text></svg>">
 <link rel="stylesheet" href="/vendor/xterm.css" />
 <link rel="stylesheet" href="/style.css" />
@@ -33,7 +33,7 @@
     <div class="sb-groups" id="sbGroups"><!-- populated by app.js --></div>
 
     <div class="sb-bottom">
-      <span class="sb-version" id="sbVersion">v4.2.0</span>
+      <span class="sb-version" id="sbVersion">v4.2.1</span>
       <div class="sb-bottom-actions">
         <button class="icon-btn" id="btnOpenAuth" title="Auth &amp; API keys">🔑</button>
         <button class="icon-btn" id="btnOpenRepl" title="Open terminal (Ctrl+`)">❭_</button>