NE Hub: Seafile, OnlyOffice, Plex, calendar and mail in one PWA

- Mobile-first PWA (phone tab bar with More menu, iPad/desktop rail)
- Passkey (WebAuthn) sign-in gates the whole app; first passkey via setup code
- Files: Seafile browse/upload/new doc/rename/move/share link/preview/delete
- In-app OnlyOffice editing with JWT-signed configs and save-back to Seafile
- Plex music player via plex.tv sign-in and a server-side proxy
- Calendar agenda from private ICS links (recurrence + time zones)
- Search, Home dashboard, webmail deep links, audiobooks frame
- Dockerfile, compose, and a Gitea Actions workflow that builds the image

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

public/index.html

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+<!doctype html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover">
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+<meta name="apple-mobile-web-app-capable" content="yes">
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+<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
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+<link rel="apple-touch-icon" href="/icon.svg">
+<link rel="stylesheet" href="/style.css">
+<title>NE Hub</title>
+</head>
+<body>
+<div id="shell">
+  <nav id="nav" aria-label="Main"></nav>
+  <div id="main"><main id="view"></main><div id="player" hidden></div></div>
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+<div id="toast" role="status"></div>
+<script src="/webauthn.js"></script>
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+</body>
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