Add advanced search engine with inverted index, thread pool execution, configuration API, and comprehensive diagnostics

frontend/style.css

@@ -1347,6 +1347,39 @@ select {
   to { transform: rotate(360deg); }
 }
 
+/* --- Search progress bar --- */
+.search-progress-bar {
+  position: fixed;
+  top: 0;
+  left: 0;
+  right: 0;
+  height: 3px;
+  z-index: 9999;
+  background: transparent;
+  pointer-events: none;
+  opacity: 0;
+  transition: opacity 0.15s;
+}
+.search-progress-bar.active {
+  opacity: 1;
+}
+.search-progress-bar .search-progress-bar__fill {
+  height: 100%;
+  background: var(--accent);
+  width: 0%;
+  animation: progress-indeterminate 1.5s ease-in-out infinite;
+}
+@keyframes progress-indeterminate {
+  0%   { width: 0%; margin-left: 0%; }
+  50%  { width: 40%; margin-left: 30%; }
+  100% { width: 0%; margin-left: 100%; }
+}
+.search-time-badge {
+  font-size: 0.7rem;
+  color: var(--text-muted);
+  margin-left: 8px;
+}
+
 /* --- Editor Modal --- */
 .editor-modal {
   display: none;
@@ -2111,6 +2144,118 @@ body.resizing-v {
   padding: 0;
 }
 
+/* --- Config rows & controls --- */
+.config-row {
+  display: grid;
+  grid-template-columns: 200px 120px 1fr;
+  align-items: center;
+  gap: 12px;
+  margin-bottom: 10px;
+}
+.config-label {
+  font-size: 0.82rem;
+  color: var(--text-primary);
+  font-weight: 500;
+}
+.config-input--num {
+  flex: none;
+  width: 120px;
+  text-align: right;
+}
+.config-hint {
+  font-size: 0.72rem;
+  color: var(--text-muted);
+}
+.config-badge-restart {
+  display: inline-block;
+  font-size: 0.65rem;
+  font-weight: 500;
+  padding: 2px 8px;
+  border-radius: 4px;
+  background: var(--danger-bg, #3d1a18);
+  color: var(--danger, #ff7b72);
+  vertical-align: middle;
+  margin-left: 6px;
+}
+.config-actions-row {
+  display: flex;
+  gap: 8px;
+  margin-top: 16px;
+  flex-wrap: wrap;
+}
+.config-btn-save {
+  padding: 8px 20px;
+  border: 1px solid var(--accent);
+  border-radius: 6px;
+  background: var(--accent);
+  color: #fff;
+  font-family: 'JetBrains Mono', monospace;
+  font-size: 0.8rem;
+  font-weight: 600;
+  cursor: pointer;
+  transition: opacity 150ms;
+}
+.config-btn-save:hover { opacity: 0.9; }
+.config-btn-secondary {
+  padding: 8px 16px;
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  background: var(--bg-secondary);
+  color: var(--text-primary);
+  font-family: 'JetBrains Mono', monospace;
+  font-size: 0.8rem;
+  cursor: pointer;
+  transition: background 150ms;
+}
+.config-btn-secondary:hover { background: var(--bg-hover); }
+
+/* --- Config diagnostics panel --- */
+.config-diagnostics {
+  background: var(--code-bg);
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  padding: 14px 16px;
+  font-family: 'JetBrains Mono', monospace;
+  font-size: 0.78rem;
+  line-height: 1.7;
+  color: var(--text-secondary);
+}
+.config-diag-loading {
+  color: var(--text-muted);
+}
+.config-diag-row {
+  display: flex;
+  justify-content: space-between;
+}
+.config-diag-row .diag-label { color: var(--text-secondary); }
+.config-diag-row .diag-value { color: var(--text-primary); font-weight: 500; }
+.config-diag-section {
+  margin-bottom: 8px;
+  padding-bottom: 8px;
+  border-bottom: 1px solid var(--border);
+}
+.config-diag-section:last-child {
+  margin-bottom: 0;
+  padding-bottom: 0;
+  border-bottom: none;
+}
+.config-diag-section-title {
+  font-weight: 600;
+  color: var(--accent);
+  margin-bottom: 4px;
+  font-size: 0.75rem;
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+}
+
+@media (max-width: 768px) {
+  .config-row {
+    grid-template-columns: 1fr;
+    gap: 4px;
+  }
+  .config-input--num { width: 100%; }
+}
+
 /* --- Toast notifications --- */
 .toast-container {
   position: fixed;