Archive Steam docs; add itch.io upload guide

Move legacy Steam-related docs into documentation/archived and add a new UPLOAD-ITCH.md describing how to publish builds to itch.io with Butler. Update top-level README to state official releases will be on itch.io. Remove Steam-specific UI/features: drop steamCloudOptIn from first-run preferences, remove the Steam Cloud teaser and summary from the setup flow, and adjust settings/setup copy to reference handheld devices and non‑Steam distribution. Also make a small wording tweak in the plugins doc about rendererPreload.

renderer/settings.html

@@ -36,7 +36,7 @@
         <!-- Big Picture Mode -->
         <div class="setting-group">
           <h3>Big Picture Mode</h3>
-          <p class="note">A controller-friendly UI designed for Steam Deck and handheld devices.</p>
+          <p class="note">A controller-friendly UI designed for handheld devices (e.g., Steam Deck).</p>
           <div class="setting-row">
             <button id="launch-bigpicture-btn" class="primary-btn">
               <span style="font-size: 18px;"></span> Launch Big Picture Mode
@@ -287,7 +287,7 @@
 
         <div class="customization-group">
           <h3>Security Updates</h3>
-          <p class="note" style="margin-bottom: 12px;">Nebula Browser is distributed via Steam, but the Electron runtime can be updated separately for security patches and performance improvements.</p>
+          <p class="note" style="margin-bottom: 12px;">Nebula Browser is distributed via itch.io and other non‑Steam channels; the Electron runtime can be updated separately for security patches and performance improvements.</p>
 
           <div class="stack">
             <!-- Update Status Banner -->

renderer/setup.html

@@ -111,7 +111,7 @@
       </div>
     </div>
 
-    <!-- Step 4: Complete (Future: Steam Cloud) -->
+    <!-- Step 4: Complete -->
     <div class="setup-step" data-step="4">
       <div class="step-content">
         <div class="success-icon">✓</div>
@@ -120,13 +120,8 @@
         <div class="completion-summary" id="completion-summary">
           <!-- Summary will be populated dynamically -->
         </div>
-        <div class="future-feature-teaser">
-          <h3>Coming Soon: Steam Cloud Sync</h3>
-          <p class="teaser-text">
-            <span class="teaser-icon">☁️</span>
-            In Phase 2, you'll be able to sync your bookmarks, settings, and themes across devices using Steam Cloud.
-          </p>
-        </div>
+        
+       
       </div>
       <div class="step-actions">
         <button class="btn btn-primary btn-large" id="btn-finish">Start Browsing</button>

renderer/setup.js

@@ -416,13 +416,6 @@ function renderCompletionSummary() {
         <div class="summary-value">${setupState.defaultBrowserSet ? 'Set as Default' : 'Not Set'}</div>
       </div>
     </div>
-    <div class="summary-item">
-      <div class="summary-icon">☁️</div>
-      <div class="summary-content">
-        <div class="summary-label">Steam Cloud Sync</div>
-        <div class="summary-value">Coming in Phase 2</div>
-      </div>
-    </div>
   `;
 }