Give episode pages margins and centre the player bar

The player, transcript and nav sections had no width constraint at all, so
they ran edge to edge while .page-header above them sat in the site's usual
900px centred container.

- Transcript now sits in a 680px centred column at 1.05rem/1.7, which holds
  the measure near 75 characters per line; 900px runs past 90, which is tiring
  over a full transcript. Gutters are 1.5rem, tightening to 1.15rem under 600px
- Player bar is centred at max-width 640px instead of stretching the column,
  and goes full width on phones
- Bumped the stylesheet cache-buster to v=8 and regenerated all 58 episode
  pages so existing transcripts pick the styles up

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

website/404.html

@@ -15,7 +15,7 @@
   <link rel="icon" type="image/png" sizes="16x16" href="favicon-16.png">
   <link rel="apple-touch-icon" href="apple-touch-icon.png">
 
-  <link rel="stylesheet" href="css/style.css?v=7">
+  <link rel="stylesheet" href="css/style.css?v=8">
   <script defer data-domain="lukeattheroost.com" data-api="/p/event" src="/p/script"></script>
   <script>window.plausible = window.plausible || function() { (window.plausible.q = window.plausible.q || []).push(arguments) }</script>
 </head>