feat: UI improvements with icons, back navigation, and overview cards

- Move AI Chat and MCP Servers from sidebar to overview page as cards
- Remove Graph from sidebar (accessible from repositories page)
- Add back buttons to all drill-down pages (finding detail, graph, chat, etc.)
- Replace text labels with icons + tooltips on action buttons and status badges
- Improve spacing and margins across tables and cards

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

compliance-dashboard/assets/main.css

@@ -323,6 +323,25 @@ code {
 
 /* ── Page Header ── */
 
+/* ── Back Navigation ── */
+
+.back-nav {
+    margin-bottom: 12px;
+}
+
+.btn-back {
+    display: inline-flex;
+    align-items: center;
+    gap: 6px;
+    font-size: 13px;
+    padding: 6px 12px;
+    color: var(--text-secondary);
+}
+
+.btn-back:hover {
+    color: var(--text-primary);
+}
+
 .page-header {
     margin-bottom: 28px;
     padding-bottom: 20px;
@@ -479,7 +498,7 @@ th {
 }
 
 td {
-    padding: 11px 16px;
+    padding: 12px 16px;
     border-bottom: 1px solid var(--border);
     font-size: 13.5px;
     color: var(--text-primary);
@@ -505,7 +524,8 @@ tbody tr:last-child td {
 .badge {
     display: inline-flex;
     align-items: center;
-    padding: 3px 10px;
+    gap: 5px;
+    padding: 4px 10px;
     border-radius: 6px;
     font-family: var(--font-mono);
     font-size: 11px;
@@ -617,6 +637,96 @@ tbody tr:last-child td {
     gap: 6px;
 }
 
+.btn-icon {
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    padding: 6px 8px;
+    min-width: 32px;
+}
+
+/* ── Overview Cards Grid ── */
+
+.overview-section {
+    margin-top: 28px;
+}
+
+.overview-section-header {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    margin-bottom: 16px;
+}
+
+.overview-section-header h3 {
+    font-family: var(--font-display);
+    font-size: 18px;
+    font-weight: 700;
+    color: var(--text-primary);
+}
+
+.overview-grid {
+    display: grid;
+    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
+    gap: 14px;
+}
+
+.overview-card {
+    background: var(--bg-card);
+    border: 1px solid var(--border);
+    border-radius: var(--radius);
+    padding: 16px;
+    transition: border-color 0.2s, box-shadow 0.2s;
+    text-decoration: none;
+    color: inherit;
+    display: flex;
+    align-items: center;
+    gap: 12px;
+}
+
+.overview-card:hover {
+    border-color: var(--accent);
+    box-shadow: 0 0 16px rgba(0, 200, 255, 0.06);
+}
+
+.overview-card-icon {
+    color: var(--accent);
+    flex-shrink: 0;
+}
+
+.overview-card-body {
+    min-width: 0;
+}
+
+.overview-card-title {
+    font-weight: 600;
+    font-size: 14px;
+    color: var(--text-primary);
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+}
+
+.overview-card-sub {
+    font-size: 12px;
+    color: var(--text-secondary);
+    margin-top: 2px;
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+}
+
+.mcp-status-dot {
+    width: 8px;
+    height: 8px;
+    border-radius: 50%;
+    flex-shrink: 0;
+}
+
+.mcp-status-dot.running { background: var(--success); }
+.mcp-status-dot.stopped { background: var(--text-tertiary); }
+.mcp-status-dot.error { background: var(--danger); }
+
 .spinner {
     display: inline-block;
     width: 14px;