feat(mcp): ajoute l'outil idea_ask_agents pour la délégation parallèle (#2)

Wrapper MCP backend pur : dispatche N requêtes idea_ask_agent en parallèle
et retourne un résultat par requête, dans l'ordre, en rejetant les cibles
dupliquées avant dispatch. Aucun changement de domaine/application — pose
la primitive nécessaire au SDK (chantier feature/sdk-integration).

QA vert (ticket #2).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

crates/infrastructure/src/orchestrator/mcp/tools.rs

@@ -61,6 +61,7 @@ pub const READ_ONLY_TOOLS: &[&str] = &[
 /// Canonical write/action MCP tools denied by default.
 pub const WRITE_ACTION_TOOLS: &[&str] = &[
     "idea_ask_agent",
+    "idea_ask_agents",
     "idea_run_in_background",
     "idea_launch_agent",
     "idea_stop_agent",
@@ -125,6 +126,7 @@ pub fn tool_returns_reply(tool: &str) -> bool {
     matches!(
         tool,
         "idea_ask_agent"
+            | "idea_ask_agents"
             | "idea_list_agents"
             | "idea_context_read"
             | "idea_memory_read"
@@ -180,6 +182,32 @@ pub fn catalogue() -> Vec<ToolDef> {
                 "additionalProperties": false
             }),
         },
+        ToolDef {
+            name: "idea_ask_agents",
+            description: "Ask several IdeA agents in parallel and return one result per request, \
+                          in the same order. Each request is equivalent to one idea_ask_agent \
+                          call; duplicate targets are rejected before dispatch.",
+            input_schema: json!({
+                "type": "object",
+                "properties": {
+                    "requests": {
+                        "type": "array",
+                        "minItems": 1,
+                        "items": {
+                            "type": "object",
+                            "properties": {
+                                "target": { "type": "string", "description": "Target agent display name." },
+                                "task": { "type": "string", "description": "Task or question to send to the target agent." }
+                            },
+                            "required": ["target", "task"],
+                            "additionalProperties": false
+                        }
+                    }
+                },
+                "required": ["requests"],
+                "additionalProperties": false
+            }),
+        },
         ToolDef {
             name: "idea_run_in_background",
             description: "Run a command as a first-class IdeA background task. Returns the task id \
@@ -659,6 +687,18 @@ mod tests {
         );
     }
 
+    #[test]
+    fn ask_agents_is_classified_and_returns_inline_reply() {
+        assert_eq!(
+            tool_access("idea_ask_agents"),
+            Some(McpToolAccess::WriteAction)
+        );
+        assert!(catalogue()
+            .into_iter()
+            .any(|tool| tool.name == "idea_ask_agents"));
+        assert!(tool_returns_reply("idea_ask_agents"));
+    }
+
     #[test]
     fn run_in_background_maps_to_background_command_with_handshake_owner() {
         let cmd = map_tool_call(