feat(upload): add dynamic expiry options and modern UI theme

- Implement dynamic expiry options on the upload page based on user roles and retention policies.
- Add helper functions to build and format expiry options into human-readable labels.
- Introduce a new modern theme featuring glassmorphism, gradients, and frosted glass cards.

backend/templates/pages/home.html

@@ -4,11 +4,13 @@
 <section class="upload-view" aria-labelledby="upload-title">
   <div class="hero-copy">
     {{if .CurrentUser}}
-    <h1 id="upload-title">Upload files.</h1>
+    <p class="hero-eyebrow">Welcome back, {{.CurrentUser.Username}}</p>
+    <h1 id="upload-title">Drop it. Share it.</h1>
     <p>{{.Data.LimitSummary}}</p>
     {{else}}
+    <p class="hero-eyebrow">Welcome</p>
     <h1 id="upload-title">Send a file. Get a link.</h1>
-    <p>Anonymous, self-hosted transfers. No account required.</p>
+    <p>Fast, private transfers that expire on your terms.</p>
     {{end}}
   </div>
 
@@ -32,7 +34,6 @@
         <div class="option-grid">
           {{if .CurrentUser}}
           <label>
-            <span>Collection</span>
             <select name="collection_id">
               <option value="">Unsorted</option>
               {{range .Data.Collections}}<option value="{{.ID}}">{{.Name}}</option>{{end}}
@@ -41,10 +42,8 @@
           {{end}}
           <label>
             <span>Expires in</span>
-            <select name="max_days">
-              <option value="7">7 days</option>
-              <option value="1">1 day</option>
-              <option value="30">30 days</option>
+            <select name="expires_minutes" data-expiry-select>
+              {{range .Data.ExpiryOptions}}<option value="{{.Minutes}}"{{if eq .Minutes $.Data.DefaultExpiryMinutes}} selected{{end}}>{{.Label}}</option>{{end}}
             </select>
           </label>
           <label>