prepare app for public app store distribution

- rebrand from 습관 트래커 to 해빗랩 across templates, manifest, service worker
- add HTTPS redirect middleware for reverse-proxied deployments
- add public landing page (/) and privacy policy page with real data
  handling disclosures
- add in-app account deletion (Apple review requirement)
- add Android TWA Digital Asset Links support (/.well-known/assetlinks.json)
- add SFTP deployment script for the Synology-hosted server

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

app/templates/404.html

@@ -1,5 +1,5 @@
 {% extends "base.html" %}
-{% block title %}페이지를 찾을 수 없어요 · 습관 트래커{% endblock %}
+{% block title %}페이지를 찾을 수 없어요 · 해빗랩{% endblock %}
 {% block content %}
 <div style="min-height: 60vh; display:flex; align-items:center; justify-content:center; text-align:center;">
   <div>