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/application/src/error.rs

@@ -6,8 +6,8 @@
 //! with one error shape when building its `ErrorDTO`.
 
 use domain::ports::{
-    AgentSessionError, EmbedderError, FsError, GitError, MemoryError, ProcessError, PtyError,
-    RemoteError, RuntimeError, StoreError,
+    AgentSessionError, EmbedderError, FsError, GitError, MemoryError, ModelServerError,
+    ProcessError, PtyError, RemoteError, RuntimeError, StoreError,
 };
 use domain::{AgentId, NodeId};
 use domain::{IssueStoreError, SprintStoreError};
@@ -38,6 +38,15 @@ pub enum AppError {
     #[error("process error: {0}")]
     Process(String),
 
+    /// A local model server could not be prepared for launch.
+    #[error("model server error ({code}): {message}")]
+    ModelServer {
+        /// Stable model-server error code.
+        code: String,
+        /// Human-readable message.
+        message: String,
+    },
+
     /// A git operation failed.
     #[error("git error: {0}")]
     Git(String),
@@ -101,6 +110,7 @@ impl AppError {
             Self::FileSystem(_) => "FILESYSTEM",
             Self::Store(_) => "STORE",
             Self::Process(_) => "PROCESS",
+            Self::ModelServer { .. } => "MODEL_SERVER",
             Self::Git(_) => "GIT",
             Self::Remote(_) => "REMOTE",
             Self::AgentAlreadyRunning { .. } => "AGENT_ALREADY_RUNNING",
@@ -183,6 +193,30 @@ impl From<ProcessError> for AppError {
     }
 }
 
+impl From<ModelServerError> for AppError {
+    fn from(e: ModelServerError) -> Self {
+        Self::ModelServer {
+            code: model_server_error_code(&e).to_owned(),
+            message: e.to_string(),
+        }
+    }
+}
+
+fn model_server_error_code(err: &ModelServerError) -> &'static str {
+    match err {
+        ModelServerError::NotConfigured => "not_configured",
+        ModelServerError::Invalid(_) => "invalid",
+        ModelServerError::PermissionDenied(_) => "permission_denied",
+        ModelServerError::PathNotAccessible(_) => "path_not_accessible",
+        ModelServerError::PortOccupied(_) => "port_occupied",
+        ModelServerError::InUse(_) => "model_server_in_use",
+        ModelServerError::Probe(_) => "probe",
+        ModelServerError::Process(_) => "process",
+        ModelServerError::Store(_) => "store",
+        ModelServerError::Timeout => "timeout",
+    }
+}
+
 impl From<RuntimeError> for AppError {
     fn from(e: RuntimeError) -> Self {
         Self::Process(e.to_string())