Add OCR: image + scanned PDF support via tesseract + pdf2image

frontend/index.html

@@ -332,8 +332,8 @@
         <h2>Documents</h2>
         <div id="dropzone" class="dropzone">
           <span class="drop-icon">&#x1F4C4;</span>
-          <span class="drop-txt">Drop PDFs / TXT here<br/><small>or click to browse</small></span>
-          <input type="file" id="file-input" multiple accept=".pdf,.txt" hidden/>
+          <span class="drop-txt">Drop PDFs, TXT, or Images here<br/><small>or click to browse</small></span>
+          <input type="file" id="file-input" multiple accept=".pdf,.txt,.md,.jpg,.jpeg,.png,.tiff,.tif,.bmp,.webp" hidden/>
         </div>
         <button id="load-samples" class="btn secondary full">Load Demo Patient Docs</button>
         <div id="status" class="status info">Upload documents or load demo docs to begin.</div>