fix(shell): the dashboard switcher opens above the app navigation, not behind it

#551 adopted the shared shell, and the dashboard switcher has been unreachable
ever since. 58 e2e tests across eleven specs fail as `locator.click` timing out,
and all 240 interception lines in that run name the same element:
`[data-testid="cn-nav"] .app-navigation`. The panel slides out, it is visible,
and every click on it lands on the navigation instead.

This is a stacking context, not a z-index. The sidebar is `position: fixed`,
which escapes the scroll flow but not the stacking context. Until #551 this view
WAS the page, so there was no context to escape and nothing else claimed the
left 280px. Now it renders inside `#app-content`, a sibling of
`.app-navigation`, and NcAppNavigation carries `z-index: 1400` on itself. A
sibling with a z-index paints above the whole of a sibling subtree whose own
z-index is auto, so the sidebar's 1500 could never win: it was competing inside
a box that had already lost. Raising the number again would have changed
nothing, which is worth saying because that is the obvious first move.

The sidebar and its backdrop are therefore teleported to `body`, making them
siblings of the navigation rather than descendants of the content, which is the
only place their z-index means what it says.

The backdrop goes from 999 to 1450 while it is there. At 999 the navigation
painted over it even once teleported, so a click meant to dismiss the sidebar
navigated instead. 1450 puts it above the navigation and below the sidebar it
sits behind.

Verified locally: 682 unit tests pass, webpack build clean, eslint and prettier
clean.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Conduction Release Bot

src/components/Workspace/DashboardSwitcherSidebar.vue

@@ -802,6 +802,12 @@ export default {
 	left: 0;
 	bottom: 0;
 	width: 280px;
+	/*
+	 * Above NcAppNavigation's own 1400. This only started mattering with #551:
+	 * before the shared shell this view was the page, and nothing else claimed
+	 * the left 280px. See the Teleport in Views.vue for why the number alone
+	 * was not enough.
+	 */
 	z-index: 1500;
 	background: var(--color-main-background, #fff);
 	border-right: 1px solid var(--color-border, #e0e0e0);

src/components/Workspace/SidebarBackdrop.vue

@@ -48,7 +48,14 @@ export default {
 	left: 0;
 	right: 0;
 	bottom: 0;
-	z-index: 999;
+	/*
+	 * Above NcAppNavigation's own 1400, and below the sidebar's 1500 that it
+	 * sits behind. At 999 the navigation painted over the backdrop, so a click
+	 * meant to dismiss the sidebar navigated instead. Only meaningful together
+	 * with the Teleport in Views.vue: inside `#app-content` no value here can
+	 * beat a sibling subtree that already carries a z-index.
+	 */
+	z-index: 1450;
 	background: rgba(0, 0, 0, 0.2);
 	cursor: pointer;
 }

src/views/Views.vue

@@ -7,28 +7,49 @@
 		     `update:modelValue` — neither of which the sidebar declares —
 		     and the panel would never open. Bind both halves explicitly.
 		     Once `runtime-shell` ships and replaces this view with
-		     `WorkspaceApp.vue`, the same binding shape applies. -->
-		<DashboardSwitcherSidebar
-			:isOpen="sidebarOpen"
-			:groupName="primaryGroupName"
-			:groupDashboards="sidebarGroupDashboards"
-			:userDashboards="sidebarUserDashboards"
-			:activeDashboardId="activeDashboard?.id"
-			:allowUserDashboards="allowUserDashboards"
-			:canEdit="canEdit"
-			:defaultUuid="defaultDashboardUuid"
-			:dashboardQuotaReached="dashboardQuotaReached"
-			:dashboardQuotaTooltip="dashboardQuotaTooltip"
-			:isEditMode="isEditMode"
-			@update:open="sidebarOpen = $event"
-			@switch="onSidebarSwitch"
-			@createDashboard="onSidebarCreateDashboard"
-			@deleteDashboard="onSidebarDeleteDashboard"
-			@toggleEdit="onRowToggleEdit"
-			@openConfig="onRowOpenConfig"
-			@addCustomWidget="onRowAddCustomWidget"
-			@setDefault="onRowSetDefault" />
-		<SidebarBackdrop v-if="sidebarOpen" @close="sidebarOpen = false" />
+		     `WorkspaceApp.vue`, the same binding shape applies.
+
+		     TELEPORTED TO BODY, and the reason is a stacking context, not a
+		     z-index. The sidebar and its backdrop are `position: fixed`, but
+		     fixed positioning does not escape a stacking context — it only
+		     escapes the scroll flow. Until #551 this view WAS the page, so
+		     there was no context to escape. #551 adopted the shared shell, so
+		     this view now renders inside `#app-content`, a sibling of
+		     `.app-navigation`, and NcAppNavigation carries `z-index: 1400` on
+		     ITSELF. A sibling with a z-index paints above the whole of a
+		     sibling subtree whose own z-index is auto, so the sidebar's 1500
+		     could never win: it was competing inside a box that had already
+		     lost.
+
+		     That cost 58 e2e failures across eleven specs, every one of them
+		     `locator.click` timing out with the SAME interceptor named in the
+		     log, `[data-testid="cn-nav"] .app-navigation`. Raising the number
+		     again would not have helped. Teleporting makes the sidebar a
+		     sibling of the navigation rather than a descendant of the content,
+		     which is the only place its z-index means what it says. -->
+		<Teleport to="body">
+			<DashboardSwitcherSidebar
+				:isOpen="sidebarOpen"
+				:groupName="primaryGroupName"
+				:groupDashboards="sidebarGroupDashboards"
+				:userDashboards="sidebarUserDashboards"
+				:activeDashboardId="activeDashboard?.id"
+				:allowUserDashboards="allowUserDashboards"
+				:canEdit="canEdit"
+				:defaultUuid="defaultDashboardUuid"
+				:dashboardQuotaReached="dashboardQuotaReached"
+				:dashboardQuotaTooltip="dashboardQuotaTooltip"
+				:isEditMode="isEditMode"
+				@update:open="sidebarOpen = $event"
+				@switch="onSidebarSwitch"
+				@createDashboard="onSidebarCreateDashboard"
+				@deleteDashboard="onSidebarDeleteDashboard"
+				@toggleEdit="onRowToggleEdit"
+				@openConfig="onRowOpenConfig"
+				@addCustomWidget="onRowAddCustomWidget"
+				@setDefault="onRowSetDefault" />
+			<SidebarBackdrop v-if="sidebarOpen" @close="sidebarOpen = false" />
+		</Teleport>
 
 		<!-- Floating controls in top right.
 		     Wave3.3 removed the floating `DashboardConfigMenu` (cog) — its