ver. 0.307: check-update button + auto-generated changelog

- Add "Sprawdź aktualizacje" refresh button in admin sidebar (AJAX check without page reload)
- Add UpdateController::checkUpdate() action clearing session cache and querying update server
- Replace hand-edited changelog.php with auto-generating script (reads manifests + legacy JSON)
- Migrate all legacy changelog entries (0.300-0.001) to changelog-legacy.json

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin/templates/site/main-layout.php

@@ -44,10 +44,16 @@
       <div class="menu">
         <div class="logo sticky-top">
           shop<b>Pro</b>
-          <span>ver. <?= \Shared\Helpers\Helpers::get_version();?></span><br>
-          <? if ( $settings[ 'update' ] and \Shared\Helpers\Helpers::get_new_version() > \Shared\Helpers\Helpers::get_version() ):?>
-            <a href="/admin/update/main_view/" class="label label-danger">aktualizacja</a>
-          <? endif;?>
+          <span>ver. <?= \Shared\Helpers\Helpers::get_version();?>
+            <? if ( $settings[ 'update' ] ):?>
+              <i class="fa fa-refresh check-update-btn" id="check-update-btn" title="Sprawdź aktualizacje" style="cursor:pointer;margin-left:4px;font-size:11px;opacity:0.7;"></i>
+            <? endif;?>
+          </span><br>
+          <span id="update-badge-wrap">
+            <? if ( $settings[ 'update' ] and \Shared\Helpers\Helpers::get_new_version() > \Shared\Helpers\Helpers::get_version() ):?>
+              <a href="/admin/update/main_view/" class="label label-danger">aktualizacja</a>
+            <? endif;?>
+          </span>
         </div>
         <div class="menu-content">
           <ul>
@@ -356,6 +362,32 @@
           });
       })();
 
+      (function() {
+        $(document).off('click.checkUpdate', '#check-update-btn').on('click.checkUpdate', '#check-update-btn', function(e) {
+          e.preventDefault();
+          var $btn = $(this);
+          if ($btn.hasClass('fa-spin')) return;
+          $btn.addClass('fa-spin').css('opacity', 1);
+          $.ajax({
+            url: '/admin/update/checkUpdate/',
+            type: 'GET',
+            dataType: 'json',
+            success: function(data) {
+              $btn.removeClass('fa-spin').css('opacity', 0.7);
+              var $wrap = $('#update-badge-wrap');
+              if (data.has_update) {
+                $wrap.html('<a href="/admin/update/main_view/" class="label label-danger">aktualizacja</a>');
+              } else {
+                $wrap.html('');
+              }
+            },
+            error: function() {
+              $btn.removeClass('fa-spin').css('opacity', 0.7);
+            }
+          });
+        });
+      })();
+
       $(document).ready(function () {
         var user_agent 	= navigator.userAgent.toLowerCase();
         var click_event = user_agent.match(/(iphone|ipod|ipad)/)  ? "touchend" : "click";