feat: add upload policies, daily limits, and storage quotas

- Add environment variables to configure anonymous uploads, daily upload caps, and default user storage limits.
- Update config loader to parse and validate the new settings.
- Implement backend logic to track daily usage and active storage per user.
- Update README and `.env.example` to document the new settings and admin panels.

backend/templates/layouts/base.html

@@ -28,14 +28,12 @@
       </a>
       <div class="nav-links">
         {{if .CurrentUser}}
-        <a class="button button-ghost" href="/app">My files</a>
-        <a class="button button-ghost" href="/account/settings">Account</a>
-        <form action="/logout" method="post" class="inline-form"><button class="button button-outline" type="submit">Logout</button></form>
+        <a class="button button-ghost" href="/api">API</a>
+        <a class="button button-outline" href="/account/settings">My Account</a>
         {{else}}
         <a class="button button-ghost" href="/login">Login</a>
-        {{end}}
         <a class="button button-ghost" href="/api">API</a>
-        <a class="button button-outline" href="/healthz">Health</a>
+        {{end}}
       </div>
     </nav>
   </header>
@@ -46,7 +44,7 @@
 
   <footer class="site-footer">
     <span>{{.AppName}} · {{.CurrentYear}} · self-hosted</span>
-    <span class="footer-links"><a href="/">Upload</a>{{if .CurrentUser}}<a href="/app">My files</a>{{end}}<a href="/healthz">Health</a></span>
+    <span class="footer-links">{{if .CurrentUser}}<a href="/api">API</a><a href="/account/settings">My Account</a>{{else}}<a href="/login">Login</a><a href="/api">API</a>{{end}}</span>
   </footer>
 </body>
 </html>