feat(background): déclencheur in-app des tâches de fond via MCP idea_run_in_background (BE-1+BE-2)

Ferme la boucle B8 côté surface agent : un agent peut lancer une commande
en tâche de fond depuis l'app, sans dépendance à un déclencheur externe.

- domain : variante OrchestratorCommand::RunInBackground.
- infrastructure : outil MCP idea_run_in_background (déclaration + schéma +
  map_tool_call), tests de mapping et compteur de catalogue.
- application : handler → SpawnBackgroundCommand (owner=requester, WakeOwner).
- app-tauri : câblage .with_spawn_background_command + catalogue MCP 23→24.

Tests verts : domain 452 / application 467 / infrastructure 489 /
app-tauri 236, build --release vert.

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

crates/app-tauri/src/state.rs

@@ -41,12 +41,11 @@ use application::{
 use async_trait::async_trait;
 use domain::ports::{
     AgentContextStore, AgentRuntime, AgentSession, AgentSessionFactory, AgentWakePort,
-    BackgroundTaskPortError, BackgroundTaskRunner, BackgroundTaskStore,
-    Clock, Embedder, EmbedderEnvInspector,
-    EmbedderProfileStore, EmbedderPromptStore, EventBus, FileSystem, GitPort, IdGenerator,
-    IssueNumberAllocator, IssueStore, MemoryRecall, MemoryStore, PermissionStore, ProcessSpawner,
-    ProfileStore, ProjectStore, PtyPort, ScheduledTask, Scheduler, SkillStore, TemplateStore,
-    WakeError, WakeReason,
+    BackgroundTaskPortError, BackgroundTaskRunner, BackgroundTaskStore, Clock, Embedder,
+    EmbedderEnvInspector, EmbedderProfileStore, EmbedderPromptStore, EventBus, FileSystem, GitPort,
+    IdGenerator, IssueNumberAllocator, IssueStore, MemoryRecall, MemoryStore, PermissionStore,
+    ProcessSpawner, ProfileStore, ProjectStore, PtyPort, ScheduledTask, Scheduler, SkillStore,
+    TemplateStore, WakeError, WakeReason,
 };
 use domain::profile::{
     AgentProfile, ContextInjection, McpConfigStrategy, McpTransport, StructuredAdapter,
@@ -61,9 +60,9 @@ use serde_json::{json, Map, Value};
 use uuid::Uuid;
 
 use infrastructure::{
-    AdaptiveMemoryRecall, BackgroundCompletionSink, BackgroundTaskReadyToDeliver,
-    ClaudePermissionProjector, ClaudeTranscriptInspector, CliAgentRuntime,
-    CodexPermissionProjector, CommandBackgroundRunner, embedder_from_profile, EmbedderEnvProbe,
+    embedder_from_profile, AdaptiveMemoryRecall, BackgroundCompletionSink,
+    BackgroundTaskReadyToDeliver, ClaudePermissionProjector, ClaudeTranscriptInspector,
+    CliAgentRuntime, CodexPermissionProjector, CommandBackgroundRunner, EmbedderEnvProbe,
     FsBackgroundTaskStore, FsConversationLog, FsEmbedderProfileStore, FsEmbedderPromptStore,
     FsHandoffStore, FsIssueNumberAllocator, FsIssueStore, FsLiveStateStore, FsMemoryStore,
     FsOrchestratorWatcher, FsPermissionStore, FsProfileStore, FsProjectStore,
@@ -1992,7 +1991,10 @@ impl AppState {
             .with_background_tasks(
                 Arc::clone(&background_tasks_port),
                 Arc::clone(&clock) as Arc<dyn Clock>,
-            ),
+            )
+            // Producteur B8 côté agent MCP : `idea_run_in_background` passe par le
+            // même use case que la commande Tauri, sans aller-retour frontend.
+            .with_spawn_background_command(Arc::clone(&spawn_background_command)),
         );
 
         let stop_live_agent = Arc::new(
@@ -4104,6 +4106,7 @@ mod mcp_serve_peer_tests {
         for expected in [
             "idea_list_agents",
             "idea_ask_agent",
+            "idea_run_in_background",
             "idea_launch_agent",
             "idea_stop_agent",
             "idea_update_context",
@@ -4140,8 +4143,8 @@ mod mcp_serve_peer_tests {
         assert!(!names.contains(&"idea_reply"));
         assert_eq!(
             tools.len(),
-            23,
-            "exactly the twenty-three exposed idea_* tools; got {names:?}"
+            24,
+            "exactly the twenty-four exposed idea_* tools; got {names:?}"
         );
 
         drop(client); // EOF ⇒ serve loop ends