Harden Docker packaging and bundle frontend assets locally

- replace fragile Docker file bind mount with persistent /data storage
- add container entrypoint to link config.json from persistent storage
- tighten Docker image permissions and add a basic healthcheck
- add .dockerignore to keep git metadata and runtime files out of the image
- bundle hls.js locally instead of loading it from a CDN
- download and serve UI/theme fonts locally instead of Google Fonts
- update service worker cache entries for local assets
- refresh README to reflect local bundled assets and cleaner deployment docs

src/tpl/footer.php

@@ -1,4 +1,4 @@
-<script src="https://cdnjs.cloudflare.com/ajax/libs/hls.js/1.4.12/hls.min.js"></script>
+<script src="/assets/vendor/hls.min.js"></script>
 <script>
 <?php
 $js_dir = __DIR__ . '/../js/';

src/tpl/head.php

@@ -12,7 +12,7 @@
 <meta name="apple-mobile-web-app-capable" content="yes">
 <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
 <meta name="apple-mobile-web-app-title" content="GridTV">
-<link href="https://fonts.googleapis.com/css2?family=Share+Tech+Mono&family=Barlow+Condensed:wght@300;400;600;700&display=swap" rel="stylesheet">
+<link rel="stylesheet" href="/assets/fonts/fonts.css">
 <?php
 $css_dir = __DIR__ . '/../css/';
 $css_files = ['base', 'topbar', 'grid', 'mobile', 'player', 'modals', 'search', 'program', 'favorites', 'updater'];