style: unify all views on Mission Control V2 design tokens

- Map legacy v1 CSS variables (--nx-*, --panel, --text-*, --surface*) to V2 tokens in nexus-tokens.css
- Restyle global shell (main.css), AppSidebar, AppHeader to match V2 Sidebar/Topbar (glass, gradients, Space Grotesk)
- Add GalaxyBackground to the v1 shell in App.vue
- Replace hardcoded v1 hex colors with V2 tokens in all deviating views (Agents, Calendar, Docs, Incidents, Memory, Notifications, ProjectDetail, Security, Team, TaskDetail, Settings)
- Keep JS status colors as hex where alpha suffixes are concatenated (AgentsIndex, Team, Notifications)
- Add Settings nav item (System group) + gear icon to V2 sidebar so it shows on the dashboard
- No component or layout structure changes; LoginView and TaskBoardView untouched

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/views/SecurityView.vue

@@ -192,7 +192,7 @@ onMounted(loadStatus)
 }
 .security-card {
   border: 1px solid var(--line);
-  border-radius: 9px;
+  border-radius: var(--r);
   background: var(--panel);
   padding: 20px;
   display: flex;
@@ -204,27 +204,27 @@ onMounted(loadStatus)
   height: 40px;
   display: grid;
   place-items: center;
-  border-radius: 9px;
-  color: #a99cff;
+  border-radius: var(--r);
+  color: var(--a-mid);
   background: var(--accent-soft);
 }
 .security-card-icon.twofa-icon {
-  color: #e5b05e;
+  color: var(--st-queue);
   background: rgba(229,176,94,.1);
 }
 .security-card-icon.passkey-icon {
-  color: #6d9fe6;
+  color: var(--a-blue);
   background: rgba(109,159,230,.1);
 }
 .security-card h3 {
   margin: 0;
   font-size: 13px;
-  color: #e8eaf0;
+  color: var(--tx);
 }
 .security-value {
   font-size: 13px;
   font-weight: 600;
-  color: #e8eaf0;
+  color: var(--tx);
 }
 .policy-text {
   font-size: 11px;
@@ -234,7 +234,7 @@ onMounted(loadStatus)
 .security-desc {
   margin: 0;
   font-size: 10px;
-  color: #7e8799;
+  color: var(--tx-3);
   line-height: 1.5;
 }
 .security-detail-list {
@@ -250,14 +250,14 @@ onMounted(loadStatus)
 }
 .security-detail-label {
   font-size: 10px;
-  color: #8991a1;
+  color: var(--tx-2);
   font-weight: 500;
   text-transform: uppercase;
   letter-spacing: 0.03em;
 }
 .security-detail-value {
   font-size: 10px;
-  color: #e8eaf0;
+  color: var(--tx);
   font-weight: 500;
   text-align: right;
   word-break: break-word;
@@ -281,11 +281,11 @@ code.security-detail-value {
 }
 .status-bool.enabled {
   background: rgba(81,212,154,.1);
-  color: #51d49a;
+  color: var(--st-work);
 }
 .status-bool.disabled {
   background: rgba(225,110,117,.08);
-  color: #e16e75;
+  color: var(--st-block);
 }
 .security-status-row {
   display: flex;
@@ -293,16 +293,16 @@ code.security-detail-value {
   gap: 6px;
 }
 .check-icon {
-  color: #51d49a;
+  color: var(--st-work);
 }
 .x-icon {
-  color: #e16e75;
+  color: var(--st-block);
 }
 .enabled-text {
-  color: #51d49a;
+  color: var(--st-work);
 }
 .disabled-text {
-  color: #e16e75;
+  color: var(--st-block);
 }
 
 .memory-status {
@@ -311,11 +311,11 @@ code.security-detail-value {
   justify-content: center;
   gap: 8px;
   padding: 48px;
-  color: #7e8799;
+  color: var(--tx-3);
   font-size: 12px;
 }
 .memory-status.error {
-  color: #e16e75;
+  color: var(--st-block);
 }
 .spin {
   animation: spin 1s linear infinite;