Add repo modal tabs and grouped repo lists

Introduce a tabbed repository modal with new styling and grouped lists. Adds CSS for modal tabs and repo-owner group/divider visuals. In JS, add activeReposTab state, helper functions to infer repo owners and match remotes, and utilities to group server and local repos. Replace flat lists with serverRepoListTemplate/recentLocalReposTemplate and group local scan results; update reposModalContent to render tabbed local/server panels and bind tab click events.

frontend/css/components.css

@@ -1233,6 +1233,43 @@
   min-height: 0;
 }
 
+.gd-modal-tabs {
+  display: flex;
+  gap: 6px;
+  padding: 10px 12px;
+  border-bottom: 1px solid var(--border);
+  background: var(--bg-panel-alt);
+}
+
+.gd-modal-tab {
+  flex: 1;
+  justify-content: center;
+  padding: 7px 10px;
+  border: 1px solid var(--border);
+  border-radius: var(--radius-md);
+  background: transparent;
+  color: var(--text-muted);
+  font-size: 13px;
+  font-weight: 600;
+}
+
+.gd-modal-tab:hover {
+  background: var(--bg-hover);
+  color: var(--text-main);
+}
+
+.gd-modal-tab.active {
+  border-color: transparent;
+  background: var(--accent-strong);
+  color: #fff;
+}
+
+.gd-modal-tab-panel {
+  min-height: 430px;
+  display: flex;
+  flex-direction: column;
+}
+
 .gd-modal-two-col {
   display: grid;
   grid-template-columns: 1fr 1fr;
@@ -1252,6 +1289,10 @@
   border-left: 1px solid var(--border);
 }
 
+.gd-modal-tab-panel .gd-modal-section-alt {
+  border-left: 0;
+}
+
 .gd-modal-section-header {
   display: flex;
   align-items: center;
@@ -1318,6 +1359,10 @@
   max-height: 300px;
 }
 
+.gd-modal-tab-panel .gd-modal-scroll-list {
+  max-height: none;
+}
+
 .gd-modal-scan-list {
   display: flex;
   flex-direction: column;
@@ -1435,6 +1480,33 @@
   color: #fff;
 }
 
+.repo-owner-group {
+  padding-bottom: 6px;
+}
+
+.repo-owner-group + .repo-owner-group {
+  margin-top: 10px;
+}
+
+.repo-owner-divider {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  margin: 2px 0 4px;
+  color: var(--text-muted);
+  font-size: 11px;
+  font-weight: 700;
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+}
+
+.repo-owner-divider::after {
+  content: "";
+  flex: 1;
+  height: 1px;
+  background: var(--border);
+}
+
 /* ── Branch dialog ────────────────────────────────────────────────────────── */
 
 .modal-backdrop {