feat(ui): add dashboard sections with sidebar navigation and mock views

Add seven sidebar sections (Dashboard, Providers, Chat, Tools,
Knowledge Base, Developer, Organization) with fully rendered mock views,
nested sub-shells for Developer and Organization, and SearXNG container
for future news feed integration. Replaces the previous OverviewPage
with a news feed dashboard.

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

src/app.rs

@@ -4,8 +4,9 @@ use dioxus::prelude::*;
 /// Application routes.
 ///
 /// Public pages (`LandingPage`, `ImpressumPage`, `PrivacyPage`) live
-/// outside the `AppShell` layout. Authenticated pages like `OverviewPage`
-/// are wrapped in `AppShell` which renders the sidebar.
+/// outside the `AppShell` layout. Authenticated pages are wrapped in
+/// `AppShell` which renders the sidebar. `DeveloperShell` and `OrgShell`
+/// provide nested tab navigation within the app shell.
 #[derive(Debug, Clone, Routable, PartialEq)]
 #[rustfmt::skip]
 pub enum Route {
@@ -17,8 +18,33 @@ pub enum Route {
     PrivacyPage {},
     #[layout(AppShell)]
         #[route("/dashboard")]
-        OverviewPage {},
+        DashboardPage {},
+        #[route("/providers")]
+        ProvidersPage {},
+        #[route("/chat")]
+        ChatPage {},
+        #[route("/tools")]
+        ToolsPage {},
+        #[route("/knowledge")]
+        KnowledgePage {},
+
+        #[layout(DeveloperShell)]
+            #[route("/developer/agents")]
+            AgentsPage {},
+            #[route("/developer/flow")]
+            FlowPage {},
+            #[route("/developer/analytics")]
+            AnalyticsPage {},
+        #[end_layout]
+
+        #[layout(OrgShell)]
+            #[route("/organization/pricing")]
+            OrgPricingPage {},
+            #[route("/organization/dashboard")]
+            OrgDashboardPage {},
+        #[end_layout]
     #[end_layout]
+
     #[route("/login?:redirect_url")]
     Login { redirect_url: String },
 }