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/pages/chat.rs

@@ -0,0 +1,147 @@
+use dioxus::prelude::*;
+
+use crate::components::ChatBubble;
+use crate::models::{ChatMessage, ChatRole, ChatSession};
+
+/// ChatGPT-style chat interface with session list and message area.
+///
+/// Full-height layout: left panel shows session history,
+/// right panel shows messages and input bar.
+#[component]
+pub fn ChatPage() -> Element {
+    let sessions = use_signal(mock_sessions);
+    let mut active_session_id = use_signal(|| "session-1".to_string());
+    let mut input_text = use_signal(String::new);
+
+    // Clone data out of signals before entering the rsx! block to avoid
+    // holding a `Signal::read()` borrow across potential await points.
+    let sessions_list = sessions.read().clone();
+    let current_id = active_session_id.read().clone();
+    let active_session = sessions_list.iter().find(|s| s.id == current_id).cloned();
+
+    rsx! {
+        section { class: "chat-page",
+            div { class: "chat-sidebar-panel",
+                div { class: "chat-sidebar-header",
+                    h3 { "Conversations" }
+                    button { class: "btn-icon", "+" }
+                }
+                div { class: "chat-session-list",
+                    for session in &sessions_list {
+                        {
+                            let is_active = session.id == current_id;
+                            let class = if is_active {
+                                "chat-session-item chat-session-item--active"
+                            } else {
+                                "chat-session-item"
+                            };
+                            let id = session.id.clone();
+                            rsx! {
+                                button {
+                                    class: "{class}",
+                                    onclick: move |_| active_session_id.set(id.clone()),
+                                    div { class: "chat-session-title", "{session.title}" }
+                                    div { class: "chat-session-date", "{session.created_at}" }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            div { class: "chat-main-panel",
+                if let Some(session) = &active_session {
+                    div { class: "chat-messages",
+                        for msg in &session.messages {
+                            ChatBubble { key: "{msg.id}", message: msg.clone() }
+                        }
+                    }
+                } else {
+                    div { class: "chat-empty",
+                        p { "Select a conversation or start a new one." }
+                    }
+                }
+                div { class: "chat-input-bar",
+                    button { class: "btn-icon chat-attach-btn", "+" }
+                    input {
+                        class: "chat-input",
+                        r#type: "text",
+                        placeholder: "Type a message...",
+                        value: "{input_text}",
+                        oninput: move |evt: Event<FormData>| {
+                            input_text.set(evt.value());
+                        },
+                    }
+                    button { class: "btn-primary chat-send-btn", "Send" }
+                }
+            }
+        }
+    }
+}
+
+/// Returns mock chat sessions with sample messages.
+fn mock_sessions() -> Vec<ChatSession> {
+    vec![
+        ChatSession {
+            id: "session-1".into(),
+            title: "RAG Pipeline Setup".into(),
+            messages: vec![
+                ChatMessage {
+                    id: "msg-1".into(),
+                    role: ChatRole::User,
+                    content: "How do I set up a RAG pipeline with Ollama?".into(),
+                    attachments: vec![],
+                    timestamp: "10:30".into(),
+                },
+                ChatMessage {
+                    id: "msg-2".into(),
+                    role: ChatRole::Assistant,
+                    content: "To set up a RAG pipeline with Ollama, you'll need to: \
+                        1) Install Ollama and pull your preferred model, \
+                        2) Set up a vector database (e.g. ChromaDB), \
+                        3) Create an embedding pipeline for your documents, \
+                        4) Wire the retrieval step into your prompt chain."
+                        .into(),
+                    attachments: vec![],
+                    timestamp: "10:31".into(),
+                },
+            ],
+            created_at: "2026-02-18".into(),
+        },
+        ChatSession {
+            id: "session-2".into(),
+            title: "GDPR Compliance Check".into(),
+            messages: vec![
+                ChatMessage {
+                    id: "msg-3".into(),
+                    role: ChatRole::User,
+                    content: "What data does CERTifAI store about users?".into(),
+                    attachments: vec![],
+                    timestamp: "09:15".into(),
+                },
+                ChatMessage {
+                    id: "msg-4".into(),
+                    role: ChatRole::Assistant,
+                    content: "CERTifAI stores only the minimum data required: \
+                        email address, session tokens, and usage metrics. \
+                        All data stays on your infrastructure."
+                        .into(),
+                    attachments: vec![],
+                    timestamp: "09:16".into(),
+                },
+            ],
+            created_at: "2026-02-17".into(),
+        },
+        ChatSession {
+            id: "session-3".into(),
+            title: "MCP Server Configuration".into(),
+            messages: vec![ChatMessage {
+                id: "msg-5".into(),
+                role: ChatRole::User,
+                content: "How do I add a new MCP server?".into(),
+                attachments: vec![],
+                timestamp: "14:00".into(),
+            }],
+            created_at: "2026-02-16".into(),
+        },
+    ]
+}