feat(leaderboard): enhance header with beta indicator and tooltip

Adds a "BETA" indicator and tooltip to the leaderboard header, 
improving user awareness of the feature's status. Comments out 
conditional score indicators in the entries table to simplify 
the template and avoid unnecessary logic.

Author: rohitpaulk

app/components/leaderboard-page/entries-table/row.hbs

@@ -46,17 +46,17 @@
   </td>
   <td class="px-4 py-2 whitespace-nowrap border border-gray-200">
     <div class="flex items-center justify-end">
-      {{#if (eq @entry.score 142)}}
+      {{!-- {{#if (eq @entry.score 142)}}
         <span class="inline-block align-middle text-teal-500 triangle-up mr-1.5" aria-hidden="true">
           <EmberTooltip @text="Increased from 139 to 142 in the past month" />
         </span>
-      {{/if}}
+      {{/if}} --}}
 
-      {{#if (eq @entry.score 99)}}
+      {{!-- {{#if (eq @entry.score 99)}}
         <span class="inline-block align-middle text-red-500 triangle-down mr-1.5" aria-hidden="true">
           <EmberTooltip @text="Decreased from 199 to 99 in the past month" />
         </span>
-      {{/if}}
+      {{/if}} --}}
 
       <div class="text-xs font-mono">
         <span class="{{if this.isCurrentUser 'text-teal-600' 'text-gray-700'}}">{{@entry.score}}</span>

app/components/leaderboard-page/header.hbs

@@ -1,13 +1,14 @@
 <div class="flex items-center justify-between gap-x-6 gap-y-4 flex-wrap" ...attributes>
   <div class="flex-shrink-0">
-    <h3 class="text-2xl font-bold text-gray-800" data-test-leaderboard-title>
-      {{@selectedLanguage.name}}
-      Leaderboard
-    </h3>
-    <div class="text-xs text-gray-400" data-test-leaderboard-description>
-      Leaderboard for
-      {{@selectedLanguage.name}}
-      users
+    <div class="flex items-center gap-x-2">
+      <h3 class="text-2xl font-bold text-gray-800" data-test-leaderboard-title>
+        {{@selectedLanguage.name}}
+        Leaderboard
+      </h3>
+      <Pill @color="green">
+        BETA
+        <EmberTooltip @text="We're still working on this feature, rough edges expected!" @side="top" />
+      </Pill>
     </div>
   </div>