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/login.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">
+<meta name="theme-color" content="#0f1115">
+<link rel="icon" href="/icon.svg">
+<link rel="apple-touch-icon" href="/icon.svg">
+<link rel="stylesheet" href="/style.css">
+<title>Sign in · NE Hub</title>
+<style>
+  body { display: grid; place-items: center; min-height: 100dvh; padding: 24px; }
+  .box { width: 100%; max-width: 380px; text-align: center; }
+  .box img { width: 72px; height: 72px; border-radius: 18px; margin-bottom: 16px; }
+  .box .btn { width: 100%; justify-content: center; min-height: 52px; font-size: 17px; }
+  .box form { text-align: left; }
+</style>
+</head>
+<body>
+<div class="box">
+  <img src="/icon.svg" alt="">
+  <h1>NE Hub</h1>
+  <p class="sub" id="sub">&nbsp;</p>
+  <div id="ui"></div>
+  <div class="err" id="err" role="alert"></div>
+</div>
+<script src="/webauthn.js"></script>
+<script src="/login.js"></script>
+</body>
+</html>