Dedupe styles.css and remove remaining inline styles

- Add --font-serif/--font-mono/--font-sans tokens to :root and point
  all ~24 hardcoded font-family declarations at them
- Drop an exact-duplicate .footer-brand .knot rule
- Merge the shared background/border of .stat-card, .card,
  .login-card, and .panel into one grouped selector
- Combine .btn-outline:hover and .nav-cta:hover into one rule
- Move remaining inline style="" attributes in index.php and
  admin/index.php into named classes/rules (.about-grid h2,
  footer address/.social-row spacing, .panel-head,
  .checkbox-label-lg, .field-hint, .form-actions)

No visual changes intended — values carried over as-is.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

index.php

@@ -99,8 +99,8 @@ $siteUrl = rtrim(SITE_URL, '/');
         <div class="about-grid">
           <div class="reveal">
             <p class="eyebrow">About the Pub</p>
-            <h2 style="margin-top:0.6rem;">A proper Irish pub, right on Washington Street.</h2>
-            <p class="lede" style="margin-top:1.5rem;">The Old Fitz Public House pours a traditional Irish pub experience in the middle of Marion — no pretense, no reservations, just a good pint and a warm room. Walk in Thursday through Saturday evening, grab a seat at the bar or a table for the family, and settle in.</p>
+            <h2>A proper Irish pub, right on Washington Street.</h2>
+            <p class="lede">The Old Fitz Public House pours a traditional Irish pub experience in the middle of Marion — no pretense, no reservations, just a good pint and a warm room. Walk in Thursday through Saturday evening, grab a seat at the bar or a table for the family, and settle in.</p>
             <p class="lede">The kitchen runs until 9, the bar stays open later for snacks, and regulars and first-timers get treated the same.</p>
           </div>
           <div class="stat-card reveal">
@@ -226,7 +226,7 @@ $siteUrl = rtrim(SITE_URL, '/');
             <img class="knot" src="./assets/knot.png" alt="">
             <span>THE OLD FITZ PUBLIC HOUSE</span>
           </a>
-          <address style="margin-top:1rem;">
+          <address>
             100 N Washington Street<br>
             Marion, Indiana
           </address>
@@ -242,7 +242,7 @@ $siteUrl = rtrim(SITE_URL, '/');
         <div>
           <p class="col-title">Get in Touch</p>
           <a class="email" href="mailto:info@theoldfitzpub.com">info@theoldfitzpub.com</a>
-          <div class="social-row" style="margin-top:1rem;">
+          <div class="social-row">
             <a href="https://www.instagram.com/theoldfitzpub/?hl=en" target="_blank" rel="noopener" aria-label="Instagram">
               <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6">
                 <rect x="3" y="3" width="18" height="18" rx="5" />