feat(backend,application,frontend,domain,web-server,app-tauri): bouton Redémarrer l'agent dans la barre supérieure des cellules — #317 (QA verte)

La cellule expose un bouton Redémarrer l'agent valable pour les trois
modes de présentation (headless, TUI native, CLI custom), sans jamais
prendre la présentation pour vérité runtime.

- Application: use case RestartCellAgentRuntime validant le binding
  exact cellule/runtime via les snapshots live (RestartRuntimeNotFound,
  ConflictAgentVisibleElsewhere, AgentNotBoundToCell) puis déléguant au
  scheduler self-restart existant (schedule_cell); CellAgentPresentation
  purement informationnelle.
- Backend/app-tauri/web-server: commande restart_cell_agent sur contrat
  DTO identique Tauri/HTTP, stop borné par timeout typé
  (RestartStopTimeout), relance préservant routage TUI natif, géométrie
  de cellule (node/rows/cols) et conversation; évenements domaine
  enrichis.
- Frontend: bouton dans la barre de cellule avec confirmation,
  overlay d'état Redémarrage…/échec (libellés par code d'erreur, Fermer/
  Réessayer), gardes d'identité de cellule et de restarts externes,
  gateway/mock/http adapters et ports alignés.
- Tests: dto_agents, workstate_actions, contrats web-server,
  LayoutGrid.cellControlsLayering, adapters agent/mock/http.

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

crates/app-tauri/src/commands.rs

@@ -26,11 +26,12 @@ use application::{
     ReadAgentContextInput, ReadConversationPageInput, ReadMcpToolPermissionsInput,
     ReadMemoryIndexInput, ReadProjectContextInput, RecallMemoryInput, RenameDeviceInput,
     RenameLayoutInput, ResolveAgentPermissionsInput, ResolveAgentSystemPermissionsInput,
-    ResolveMemoryLinksInput, RevokeDeviceInput, RotateConversationLogInput, SaveChatDraftInput,
-    SetActiveLayoutInput, SetAgentMcpToolAllowedInput, SlashCommandEffect,
-    SnapshotRunningAgentsInput, StopLiveAgentInput, SyncAgentWithTemplateInput,
-    UnassignSkillFromAgentInput, UpdateAgentContactableInput, UpdateAgentContextInput,
-    UpdateAgentEffortInput, UpdateAgentMcpToolPermissionsInput, UpdateAgentPermissionsInput,
+    ResolveMemoryLinksInput, RestartCellAgentRuntimeInput, RevokeDeviceInput,
+    RotateConversationLogInput, SaveChatDraftInput, SetActiveLayoutInput,
+    SetAgentMcpToolAllowedInput, SlashCommandEffect, SnapshotRunningAgentsInput,
+    StopLiveAgentInput, SyncAgentWithTemplateInput, UnassignSkillFromAgentInput,
+    UpdateAgentContactableInput, UpdateAgentContextInput, UpdateAgentEffortInput,
+    UpdateAgentMcpToolPermissionsInput, UpdateAgentPermissionsInput,
     UpdateAgentSystemPermissionsInput, UpdateMemoryInput, UpdateProjectContextInput,
     UpdateProjectMcpToolPermissionsInput, UpdateProjectOrchestratorInput,
     UpdateProjectPermissionsInput, UpdateProjectSystemPermissionsInput, UpdateSkillInput,
@@ -73,6 +74,7 @@ use crate::dto::{
     RemoveProjectResponseDto, RenameLayoutRequestDto, ReplyChunk, ResizeTerminalRequestDto,
     ResolveAgentPermissionsRequestDto, ResolveAgentPermissionsResponseDto,
     ResolveAgentSystemPermissionsRequestDto, ResolvedAgentSystemPermissionsDto,
+    RestartCellAgentRuntimeRequestDto, RestartCellAgentRuntimeResponseDto,
     RestoreOpenProjectsOutputDto, ResumableAgentListDto, RetryOpenProjectRestoreRequestDto,
     SaveChatDraftRequestDto, SaveEmbedderProfileRequestDto, SaveModelServerRequestDto,
     SaveOpenCodeProviderProfileRequestDto, SaveOpenProjectRestoreOrderRequestDto,
@@ -2268,6 +2270,32 @@ pub async fn stop_live_agent(
         .map_err(ErrorDto::from)
 }
 
+/// Atomically restarts the runtime bound to an exact visible agent cell.
+///
+/// The presentation hint is retained for correlation only. Runtime selection,
+/// stop ordering and relaunch are owned by the backend restart coordinator.
+#[tauri::command]
+pub async fn restart_cell_agent_runtime(
+    request: RestartCellAgentRuntimeRequestDto,
+    state: State<'_, AppState>,
+) -> Result<RestartCellAgentRuntimeResponseDto, ErrorDto> {
+    let project = resolve_project(&request.project_id, &state).await?;
+    let output = state
+        .restart_cell_agent_runtime
+        .execute(RestartCellAgentRuntimeInput {
+            project,
+            node_id: parse_node_id(&request.node_id)?,
+            agent_id: parse_agent_id(&request.agent_id)?,
+            presentation: request.presentation.into(),
+            layout_id: request
+                .layout_id
+                .as_deref()
+                .map(parse_layout_id)
+                .transpose()?,
+        })?;
+    Ok(output.into())
+}
+
 /// `read_agent_context` — read an agent's Markdown context.
 ///
 /// # Errors