feat: implement client backend

This includes temporary AI-generated frontend scaffolding, none of this will be used in production. It was just used during development for the backend.

ui/types.slint

@@ -0,0 +1,70 @@
+/// TEMPORARY AI GENERATED FRONTEND \\\
+///   NOT TO BE USED IN PRODUCTION  \\\
+
+// Data shapes shared between Rust and Slint. Rust fills models of these; the UI
+// only renders them. Keep them flat and dumb.
+
+export enum Screen { loading, login, main }
+export enum ChannelKind { text, voice, category }
+export enum MessageKind { message, date-divider, notice, start-of-room }
+
+// A Discord "server" == a top-level Matrix Space.
+export struct ServerItem {
+    id: string,
+    name: string,
+    initial: string,
+    color: color,
+    unread: bool,
+    mentions: int,
+}
+
+// A Discord "channel" == a Matrix room. A "category" == a sub-space.
+// In Home mode the same struct carries DMs (is-dm = true).
+export struct ChannelItem {
+    id: string,
+    name: string,
+    topic: string,
+    kind: ChannelKind,
+    unread: bool,
+    mentions: int,
+    joined: bool,
+    is-dm: bool,
+    initial: string,
+    color: color,
+}
+
+export struct ReactionItem {
+    key: string,
+    count: int,
+    mine: bool,
+}
+
+// One row of the message list. Date dividers, notices and the "start of room"
+// banner are rows too, so the list is a single flat model.
+export struct MessageItem {
+    id: string,
+    kind: MessageKind,
+    sender: string,
+    initial: string,
+    color: color,
+    body: string,
+    time: string,
+    short-time: string,
+    show-header: bool,
+    edited: bool,
+    own: bool,
+    pending: bool,
+    has-reply: bool,
+    reply-sender: string,
+    reply-body: string,
+    reactions: [ReactionItem],
+}
+
+// Member list rows. Header rows ("ADMINS — 2") are rows too.
+export struct MemberItem {
+    id: string,
+    name: string,
+    initial: string,
+    color: color,
+    is-header: bool,
+}