feat(model-server): backend modèles locaux — serveur llama.cpp intégré (#35) et profils OpenCode locaux multiples (#36)

Sprint « Modeles locaux », couche backend (domain/application/infra/app-tauri).

#35 — Serveur de modèle local intégré (llama.cpp) :
- domain: model_server.rs (agrégat + statut), ports ModelServerProbe /
  ManagedProcess / ModelServerRuntime / ModelServerRegistry, événements
  model_server_status_changed et agent_launch_failed.
- application: use case EnsureLocalModelServer branché sur LaunchAgent.
- infrastructure: adapters HttpOpenAiCompatibleProbe, LlamaCppRuntime,
  LocalManagedProcess, FsModelServerRegistry.
- app-tauri: DTO plat LocalModelServerConfigDto, commandes
  list/save/delete_model_server avec garde model_server_in_use, wiring.

#36 — Profils OpenCode locaux multiples :
- domain: VO LocalModelServerId, OpenCodeConfig.local_model_server_id.
- application: use case CloneOpenCodeProfileFromSeed.
- app-tauri: commande clone_opencode_profile_from_seed, DTO/wiring.

Tests verts (exécution réelle) : domain+application OK, app-tauri
dto_model_servers 3/3 et dto_profiles 10/10, infra model_server 2/2,
application model_server+profile_usecases 19/19, cargo build workspace Finished.

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

crates/domain/src/events.rs

@@ -3,7 +3,8 @@
 
 use crate::conversation::ConversationParty;
 use crate::ids::{
-    AgentId, IssueId, ProfileId, ProjectId, SessionId, SkillId, SprintId, TaskId, TemplateId,
+    AgentId, IssueId, LocalModelServerId, ProfileId, ProjectId, SessionId, SkillId, SprintId,
+    TaskId, TemplateId,
 };
 use crate::issue::{IssueLinkKind, IssuePriority, IssueRef, IssueStatus, IssueVersion};
 use crate::mailbox::TicketId;
@@ -46,6 +47,24 @@ pub enum DomainEvent {
         /// The session it runs in.
         session_id: SessionId,
     },
+    /// An agent launch failed before a runtime session could be created.
+    AgentLaunchFailed {
+        /// The agent whose launch failed.
+        agent_id: AgentId,
+        /// Failure cause namespace.
+        cause: String,
+        /// Stable error code.
+        code: String,
+        /// Human-readable message.
+        message: String,
+    },
+    /// A local model-server status changed while preparing a launch.
+    ModelServerStatusChanged {
+        /// The local model server.
+        server_id: LocalModelServerId,
+        /// New lifecycle status.
+        status: crate::model_server::ModelServerLifecycleStatus,
+    },
     /// A first-class background task started running.
     BackgroundTaskStarted {
         /// The owning project.