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

README.md

@@ -45,7 +45,7 @@ This demo runs with sample XMLTV feeds to showcase the interface.
 - ⚙️ **Re-editable setup** — protected by an admin key, no SSH required to update config
 - 🔔 **Update notifications** — a badge appears in the topbar when a new release is available on GitHub
 - 🔄 **Auto-reload** EPG every 30 minutes
-- 0️⃣ **Zero JS dependencies** — vanilla PHP, hls.js loaded from CDN
+- 0️⃣ **Zero build tooling** — vanilla PHP/JS/CSS, with bundled local assets
 
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