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/backend/src/dto.rs

@@ -12,13 +12,14 @@ use serde_json::Value;
 
 use application::{
     AgentBackgroundTaskState, AgentTicketState, AppError, AppExitWorkGuardDetail,
-    AppExitWorkGuardState, AttachLiveAgentOutput, BackgroundTaskKindLabel,
+    AppExitWorkGuardState, AttachLiveAgentOutput, BackgroundTaskKindLabel, CellAgentPresentation,
     ConversationPreviewStatus, ConversationTurnWorkPreview, ConversationWorkSummary,
     CreateProjectInput, CreateProjectOutput, ExecuteSlashCommandOutput, GitGraphOutput,
     HealthInput, HealthReport, LayoutKind, ListProjectsOutput, ListSlashCommandsOutput,
     LiveRuntimeState, LiveSessionKind, LiveSessionSnapshot, OpenProjectOutput, ProjectWorkState,
-    RestoreOpenProjectFailure, RestoreOpenProjectsOutput, SlashCommandEffect, StopLiveAgentOutput,
-    TicketWorkSource, TicketWorkStatus, TurnPage, TurnSource, TurnView,
+    RestartCellAgentRuntimeOutput, RestoreOpenProjectFailure, RestoreOpenProjectsOutput,
+    SlashCommandEffect, StopLiveAgentOutput, TicketWorkSource, TicketWorkStatus, TurnPage,
+    TurnSource, TurnView,
 };
 use domain::ports::{ReplyProgress, ReplyProgressKind, ReplyProgressSource, ReplyProgressStage};
 use domain::{
@@ -4611,6 +4612,98 @@ pub struct StopLiveAgentRequestDto {
     pub reason: Option<String>,
 }
 
+/// Informational presentation supplied by the cell that requests a restart.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum CellAgentPresentationDto {
+    /// Background/headless orchestration surface.
+    Headless,
+    /// Native interactive provider terminal.
+    Tui,
+    /// IdeA structured/custom CLI chat.
+    CustomCli,
+    /// Presentation cannot be determined by the caller.
+    Unknown,
+}
+
+impl From<CellAgentPresentationDto> for CellAgentPresentation {
+    fn from(value: CellAgentPresentationDto) -> Self {
+        match value {
+            CellAgentPresentationDto::Headless => Self::Headless,
+            CellAgentPresentationDto::Tui => Self::Tui,
+            CellAgentPresentationDto::CustomCli => Self::CustomCli,
+            CellAgentPresentationDto::Unknown => Self::Unknown,
+        }
+    }
+}
+
+impl From<CellAgentPresentation> for CellAgentPresentationDto {
+    fn from(value: CellAgentPresentation) -> Self {
+        match value {
+            CellAgentPresentation::Headless => Self::Headless,
+            CellAgentPresentation::Tui => Self::Tui,
+            CellAgentPresentation::CustomCli => Self::CustomCli,
+            CellAgentPresentation::Unknown => Self::Unknown,
+        }
+    }
+}
+
+/// Request for an atomic restart of the runtime bound to one agent cell.
+#[derive(Debug, Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct RestartCellAgentRuntimeRequestDto {
+    /// Owning project registry id.
+    pub project_id: String,
+    /// Exact hosting layout leaf.
+    pub node_id: String,
+    /// Agent expected to be bound to the leaf.
+    pub agent_id: String,
+    /// Informational presentation; the backend resolves the real runtime.
+    #[serde(default = "unknown_cell_agent_presentation")]
+    pub presentation: CellAgentPresentationDto,
+    /// Optional named layout id when already known by the caller.
+    #[serde(default)]
+    pub layout_id: Option<String>,
+}
+
+fn unknown_cell_agent_presentation() -> CellAgentPresentationDto {
+    CellAgentPresentationDto::Unknown
+}
+
+/// Immediate acknowledgement for an accepted cell restart.
+#[derive(Debug, Clone, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct RestartCellAgentRuntimeResponseDto {
+    /// Correlation id used by `agentRestart*` events.
+    pub restart_id: String,
+    /// Stable acknowledgement state.
+    pub status: &'static str,
+    /// Validated agent id.
+    pub agent_id: String,
+    /// Validated node id.
+    pub node_id: String,
+    /// Actual live runtime family (`pty` or `structured`).
+    pub kind: LiveWorkSessionKindDto,
+    /// Informational presentation echoed to the caller.
+    pub presentation: CellAgentPresentationDto,
+    /// Optional layout id echoed to the caller.
+    pub layout_id: Option<String>,
+}
+
+impl From<RestartCellAgentRuntimeOutput> for RestartCellAgentRuntimeResponseDto {
+    fn from(out: RestartCellAgentRuntimeOutput) -> Self {
+        Self {
+            restart_id: out.restart_id,
+            status: "scheduled",
+            agent_id: out.agent_id.to_string(),
+            node_id: out.node_id.to_string(),
+            kind: out.kind.into(),
+            presentation: out.presentation.into(),
+            layout_id: out.layout_id.map(|id| id.to_string()),
+        }
+    }
+}
+
 /// Response DTO for `stop_live_agent`: the torn-down session's coordinates.
 #[derive(Debug, Clone, Serialize)]
 #[serde(rename_all = "camelCase")]