web: fix homepage hero misalignment after removing the globe

.hero-inner uses a 2-col grid (1.05fr 0.95fr) that assumed the Earth canvas in
the right column; with the globe removed the content was cramped left with a
big empty column. Add .hero-inner--single (1fr, max-width 640px) and apply it on
the homepage so the hero text stacks cleanly.

web/assets/style.css

@@ -50,6 +50,7 @@ code{font-family:"JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,"Co
 /* hero — two columns */
 .hero{max-width:var(--maxw);margin:0 auto;padding:70px 22px 40px}
 .hero-inner{display:grid;grid-template-columns:1.05fr 0.95fr;gap:40px;align-items:center}
+.hero-inner--single{grid-template-columns:1fr;max-width:640px}
 .hero-badge{display:inline-block;font-size:12.5px;letter-spacing:.4px;color:var(--muted);border:1px solid var(--line);border-radius:999px;padding:5px 14px;margin-bottom:20px}
 .hero h1{font-size:clamp(32px,5vw,52px);font-weight:800;letter-spacing:-1px;line-height:1.08}
 .accent{color:var(--accent)}

web/index.php

@@ -7,7 +7,7 @@ pmm_header('home', '跨平台 C 语言包管理器');
 ?>
 
 <header id="top" class="hero">
-  <div class="hero-inner">
+  <div class="hero-inner hero-inner--single">
     <div class="hero-badge">v<?php echo PMM_VERSION; ?> · C11 · Windows / Linux / macOS</div>
     <h1>ParlzPackageManager <span class="accent">(PMM)</span></h1>
     <p class="hero-tag">一个用 <strong>C 语言</strong>从零编写的跨平台包管理器。像 apt 一样多用镜像源，也能直接从 <strong>GitHub / GitLab / Gitea / Forgejo</strong> Release 装包。</p>