feat(model-server): afficher le téléchargement du modèle llamacpp au démarrage (#54)

Ajoute un handle du téléchargement des modèles lors du démarrage de
llamacpp : le domaine et l'application émettent la progression de
téléchargement du modèle, relayée en événement côté app-tauri, et l'UI
l'affiche via un badge de lancement et un overlay de cellule pendant que
le serveur de modèle démarre.

Backend (B1) : progression de téléchargement dans domain/application,
relais d'événement app-tauri, couverture de tests.
Frontend (F1) : modelServerLaunch, badge et overlay LayoutGrid, tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/domain/src/events.rs

@@ -33,7 +33,7 @@ pub enum OrchestrationSource {
 /// concern relayed to IPC by an infrastructure adapter, which owns the wire
 /// format. `PtyOutput` in particular is usually short-circuited to a Tauri
 /// channel rather than serialised here.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
 pub enum DomainEvent {
     /// A project was created.
     ProjectCreated {

crates/domain/src/model_server.rs

@@ -494,7 +494,7 @@ pub struct ModelServerReady {
 }
 
 /// Lifecycle status emitted for presentation.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
 pub enum ModelServerLifecycleStatus {
     /// No local model server is configured for the profile.
     NotConfigured,
@@ -502,6 +502,17 @@ pub enum ModelServerLifecycleStatus {
     Probing,
     /// IdeA is starting the server.
     Starting,
+    /// The server process is alive but still downloading/preparing a remote model.
+    Downloading {
+        /// Downloaded bytes when known.
+        downloaded_bytes: Option<u64>,
+        /// Total bytes when known.
+        total_bytes: Option<u64>,
+        /// Completion percentage when known.
+        percent: Option<f32>,
+        /// Remote model source, for example a Hugging Face repository id.
+        source: Option<String>,
+    },
     /// The server is ready.
     Ready {
         /// `true` when an already-running server was reused.