feat: add remove blank pages tool with sensitivity control

Implement new tool to detect and remove blank pages from PDFs with configurable sensitivity. Includes UI with preview functionality and comprehensive tests.

src/js/ui.ts

@@ -1794,4 +1794,29 @@ posterize: () => `
     </div>
 `,
 
+'remove-blank-pages': () => `
+    <h2 class="text-2xl font-bold text-white mb-4">Remove Blank Pages</h2>
+    <p class="mb-6 text-gray-400">Automatically detect and remove blank or nearly blank pages from your PDF. Adjust the sensitivity to control what is considered "blank".</p>
+    ${createFileInputHTML()}
+    <div id="file-display-area" class="mt-4 space-y-2"></div>
+
+    <div id="remove-blank-options" class="hidden mt-6 space-y-4">
+        <div>
+            <label for="sensitivity-slider" class="block mb-2 text-sm font-medium text-gray-300">
+                Sensitivity (<span id="sensitivity-value">99</span>%)
+            </label>
+            <input type="range" id="sensitivity-slider" min="80" max="100" value="99" class="w-full">
+            <p class="text-xs text-gray-400 mt-1">Higher sensitivity requires pages to be more "blank" to be removed.</p>
+        </div>
+        
+        <div id="analysis-preview" class="hidden p-4 bg-gray-900 border border-gray-700 rounded-lg">
+             <h3 class="text-lg font-semibold text-white mb-2">Analysis Results</h3>
+             <p id="analysis-text" class="text-gray-300"></p>
+             <div id="removed-pages-thumbnails" class="mt-4 grid grid-cols-5 sm:grid-cols-8 md:grid-cols-10 gap-2"></div>
+        </div>
+
+        <button id="process-btn" class="btn-gradient w-full mt-6">Remove Blank Pages & Download</button>
+    </div>
+`,
+
 };