feat: initialize warpbox.dev project structure and backend

Initialize the repository with the core Go backend architecture and a frontend mockup for warpbox.dev, a self-hosted file-sharing application.

- Set up Go backend modules for configuration, HTTP server, middleware, handlers, and templates.
- Add local development scripts, environment templates, and basic project configuration.
- Include a React-based frontend mockup under the docs directory.

backend/templates/pages/home.gohtml

@@ -0,0 +1,46 @@
+{{define "home.gohtml"}}{{template "base" .}}{{end}}
+
+{{define "content"}}
+<section class="upload-view" aria-labelledby="upload-title">
+  <form class="upload-panel" action="/api/v1/upload" method="post" enctype="multipart/form-data">
+    <div class="panel-header">
+      <h1 id="upload-title">Upload your files</h1>
+      <p>Drag files here or choose them from your device.</p>
+    </div>
+
+    <label class="drop-zone" for="file-input">
+      <span class="drop-icon" aria-hidden="true">+</span>
+      <span class="drop-title">Drop files to upload</span>
+      <span class="drop-copy">Click to browse</span>
+      <input id="file-input" name="file" type="file" multiple>
+    </label>
+
+    <details class="advanced-options">
+      <summary>Advanced options</summary>
+      <div class="option-grid">
+        <label>
+          <span>Expires after</span>
+          <select name="max_days">
+            <option value="7">7 days</option>
+            <option value="1">1 day</option>
+            <option value="30">30 days</option>
+          </select>
+        </label>
+        <label>
+          <span>Max downloads</span>
+          <input type="number" name="max_downloads" min="1" placeholder="Unlimited">
+        </label>
+        <label>
+          <span>Password</span>
+          <input type="password" name="password" autocomplete="new-password" placeholder="Optional">
+        </label>
+      </div>
+    </details>
+
+    <div class="form-footer">
+      <p>Current max file size: {{.Data.MaxUploadSize}}</p>
+      <button class="button button-primary" type="submit">Upload files</button>
+    </div>
+  </form>
+</section>
+{{end}}