Implement multi-stage Docker build with security hardening, add health check endpoint, optimize in-memory search with O(1) wikilink lookup, extract inline tags from markdown content, and enhance documentation with architecture diagrams and performance metrics

frontend/style.css

@@ -26,6 +26,10 @@
   --scrollbar: #30363d;
   --resize-handle: #30363d;
   --overlay-bg: rgba(0,0,0,0.5);
+  --danger: #ff7b72;
+  --danger-bg: #3d1a18;
+  --success: #3fb950;
+  --success-bg: #1a3d1f;
 }
 
 /* ===== THEME — LIGHT ===== */
@@ -47,6 +51,10 @@
   --scrollbar: #d0d7de;
   --resize-handle: #d0d7de;
   --overlay-bg: rgba(0,0,0,0.3);
+  --danger: #cf222e;
+  --danger-bg: #ffebe9;
+  --success: #1a7f37;
+  --success-bg: #dafbe1;
 }
 
 /* ===== BASE ===== */
@@ -1382,8 +1390,8 @@ select {
   opacity: 0.9;
 }
 .editor-btn.danger:hover {
-  color: #ff7b72;
-  border-color: #ff7b72;
+  color: var(--danger);
+  border-color: var(--danger);
 }
 .editor-body {
   flex: 1;
@@ -2059,3 +2067,55 @@ body.resizing-v {
   border: none;
   padding: 0;
 }
+
+/* --- Toast notifications --- */
+.toast-container {
+  position: fixed;
+  bottom: 20px;
+  left: 50%;
+  transform: translateX(-50%);
+  z-index: 10000;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 8px;
+  pointer-events: none;
+}
+.toast {
+  padding: 10px 20px;
+  border-radius: 8px;
+  font-family: 'JetBrains Mono', monospace;
+  font-size: 0.82rem;
+  color: var(--text-primary);
+  background: var(--bg-secondary);
+  border: 1px solid var(--border);
+  box-shadow: 0 8px 24px rgba(0,0,0,0.3);
+  opacity: 0;
+  transform: translateY(12px);
+  transition: opacity 250ms ease, transform 250ms ease;
+  pointer-events: auto;
+  max-width: 420px;
+  text-align: center;
+}
+.toast.show {
+  opacity: 1;
+  transform: translateY(0);
+}
+.toast-error {
+  border-color: var(--danger);
+  background: var(--danger-bg);
+  color: var(--danger);
+}
+.toast-success {
+  border-color: var(--success);
+  background: var(--success-bg);
+  color: var(--success);
+}
+
+/* --- Tree loading indicator --- */
+.tree-loading {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 8px 16px;
+}