ui: 5 polish fixes

1. Rename 'Annotation Tool' → 'Data Use Annotation Tool'
2. Remove redundant 'PDF Viewer' heading
3. Compact document dropdown (smaller font/padding, max-width)
4. PDF viewer defaults to 75% zoom
5. Annotation panel stays closed after save

app/components/PdfViewer.js

@@ -25,7 +25,7 @@ export default function PdfViewer({ pdfUrl, pageNumber }) {
 
     // Proxy the PDF through our own API to bypass CORS restrictions.
     // Then use the browser's built-in PDF viewer via <object> tag.
-    const proxyUrl = `/api/pdf-proxy?url=${encodeURIComponent(pdfUrl)}#page=${viewerPage}`;
+    const proxyUrl = `/api/pdf-proxy?url=${encodeURIComponent(pdfUrl)}#page=${viewerPage}&zoom=75`;
 
     return (
         <div className="pdf-container">

app/globals.css

@@ -440,11 +440,12 @@ h4 {
   background-color: var(--surface);
   color: var(--text-color);
   border: 1px solid var(--border-color);
-  border-radius: 8px;
-  padding: 8px 12px;
-  font-size: 0.9rem;
+  border-radius: 6px;
+  padding: 4px 8px;
+  font-size: 0.75rem;
   cursor: pointer;
   transition: border-color 0.2s;
+  max-width: 280px;
 }
 
 .select-group select:hover,

app/page.js

@@ -304,7 +304,6 @@ export default function Home() {
                 setAnnotations(prev => [...prev, payload]);
                 setModalOpen(false);
                 showToast("Annotation saved!");
-                setPanelOpen(true);
                 refreshPageData(); // Refresh so new annotation appears highlighted
             } else {
                 showToast("Failed to save annotation.", "error");
@@ -424,8 +423,8 @@ export default function Home() {
         return (
             <div className="login-gate">
                 <div className="login-card">
-                    <h1>🔒 Annotation Tool</h1>
-                    <p>Sign in with your HuggingFace account to access the annotation tool.</p>
+                    <h1>🔒 Data Use Annotation Tool</h1>
+                    <p>Sign in with your HuggingFace account to access the tool.</p>
                     <button onClick={handleLogin} className="btn btn-login-large">
                         🤗 Sign in with HuggingFace
                     </button>
@@ -448,7 +447,7 @@ export default function Home() {
         <div className="app-wrapper">
             {/* Top bar with user identity */}
             <div className="top-bar">
-                <span className="top-bar-title">Annotation Tool</span>
+                <span className="top-bar-title">Data Use Annotation Tool</span>
                 <div className="top-bar-right">
                     <ProgressBar
                         documents={documents}
@@ -478,7 +477,7 @@ export default function Home() {
             <div className="container">
                 <div className="pane left-pane">
                     <div className="pane-header">
-                        <h2>PDF Viewer</h2>
+
                         <DocumentSelector
                             documents={documents}
                             selectedDocIndex={selectedDocIndex}