feat(dash): improved frontend dashboard (#6)

Co-authored-by: Sharang Parnerkar <parnerkarsharang@gmail.com>
Reviewed-on: #6

src/models/chat.rs

@@ -0,0 +1,71 @@
+use serde::{Deserialize, Serialize};
+
+/// The role of a participant in a chat conversation.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum ChatRole {
+    /// Message sent by the human user
+    User,
+    /// Message generated by the AI assistant
+    Assistant,
+    /// System-level instruction (not displayed in UI)
+    System,
+}
+
+/// The type of file attached to a chat message.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum AttachmentKind {
+    /// Image file (png, jpg, webp, etc.)
+    Image,
+    /// Document file (pdf, docx, txt, etc.)
+    Document,
+    /// Source code file
+    Code,
+}
+
+/// A file attachment on a chat message.
+///
+/// # Fields
+///
+/// * `name` - Original filename
+/// * `kind` - Type of attachment for rendering
+/// * `size_bytes` - File size in bytes
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct Attachment {
+    pub name: String,
+    pub kind: AttachmentKind,
+    pub size_bytes: u64,
+}
+
+/// A single message in a chat conversation.
+///
+/// # Fields
+///
+/// * `id` - Unique message identifier
+/// * `role` - Who sent this message
+/// * `content` - The message text content
+/// * `attachments` - Optional file attachments
+/// * `timestamp` - ISO 8601 timestamp string
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct ChatMessage {
+    pub id: String,
+    pub role: ChatRole,
+    pub content: String,
+    pub attachments: Vec<Attachment>,
+    pub timestamp: String,
+}
+
+/// A chat session containing a conversation history.
+///
+/// # Fields
+///
+/// * `id` - Unique session identifier
+/// * `title` - Display title (usually derived from first message)
+/// * `messages` - Ordered list of messages in the session
+/// * `created_at` - ISO 8601 creation timestamp
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct ChatSession {
+    pub id: String,
+    pub title: String,
+    pub messages: Vec<ChatMessage>,
+    pub created_at: String,
+}