feat(deck): source links for both labs, plus unslop pass and verify tune

- Add 'Source on Gitea' link next to every 'Open the X lab' link,
  pointing to https://git.marcospaulo.dev.br/netcracker/ai-for-dummies/...
- Same download links added to both SilverBullet guides (Preview +
  Source on Gitea) under Path A and Path B.
- Tighten standalone verify rule: only block external <script src> and
  <link rel=stylesheet href>. Plain <a href=https://...> hyperlinks are
  not runtime dependencies.
- Unslop pass across all deck text, SilverBullet EN/PT, hands-on/rules
  header/label/README: kill triplets, dramatic single-word sentences,
  'matrix below / looks good / cuts the opposite failure' rhetoric.
  Header subtitle now reads 'Toggle rules. Same task, different
  coverage.' (was 'different leash').

verify: all six checks pass.

hands-on/rules/index.html

@@ -10,7 +10,7 @@
   <main>
     <header>
       <div><span>HANDS-ON / RULES</span><h1>Guardrails</h1></div>
-      <p>Toggle rules. Watch the prompt change. Same task, different leash.</p>
+      <p>Toggle rules. Same task, different coverage.</p>
     </header>
 
     <section aria-labelledby="rules-heading">
@@ -27,7 +27,7 @@
       </div>
       <div class="prompt-grid">
         <article class="prompt-card" data-side="naive">
-          <header><span>NAIVE</span><h3>Vanilla ask</h3></header>
+          <header><span>NAIVE</span><h3>Plain prompt</h3></header>
           <pre id="prompt-naive"></pre>
         </article>
         <article class="prompt-card" data-side="ruled">