feat(memory): config embedders (LOT C2) + suggestion contextuelle (LOT C3) + contexte projet partagé

- LOT C2 (§14.5.3) : use cases de configuration des embedders déclaratifs
  (List/Save/Delete + DescribeEmbedderEngines : modèles ONNX recommandés,
  environnement local détecté, stratégies compilées). UI EmbedderSettings.
- LOT C3 (§14.5.5) : suggestion contextuelle best-effort à l'activation quand la
  mémoire dépasse le budget de recall sans embedder configuré (event
  EmbedderSuggested, anti-spam 1×/session, « ne plus demander »).
- Contexte projet partagé .ideai/CONTEXT.md (model-agnostic) injecté à tous les
  agents/profils au lancement, avant la persona. UI ProjectContextPanel.

Tests : backend workspace vert (0 échec) ; frontend 306/306.

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

crates/infrastructure/src/orchestrator/mod.rs

@@ -205,7 +205,10 @@ async fn scan_once(
 /// Whether `path` is a request file to process: a `.json` that is not a
 /// `.response.json` sibling we wrote ourselves.
 fn is_request_file(path: &Path) -> bool {
-    let name = path.file_name().and_then(|n| n.to_str()).unwrap_or_default();
+    let name = path
+        .file_name()
+        .and_then(|n| n.to_str())
+        .unwrap_or_default();
     name.ends_with(".json") && !name.ends_with(".response.json")
 }
 
@@ -242,14 +245,21 @@ async fn dispatch_file(
         Ok(r) => r,
         Err(e) => return OrchestratorResponse::failure(None, format!("invalid json: {e}")),
     };
-    let action = request.action.clone();
+    let action = request
+        .request_type
+        .as_ref()
+        .or(request.action.as_ref())
+        .cloned();
     let command = match request.validate() {
         Ok(c) => c,
-        Err(e) => return OrchestratorResponse::failure(Some(action), e.to_string()),
+        Err(e) => return OrchestratorResponse::failure(action, e.to_string()),
     };
     match service.dispatch(project, command).await {
-        Ok(out) => OrchestratorResponse::success(action, out.detail),
-        Err(e) => OrchestratorResponse::failure(Some(action), e.to_string()),
+        Ok(out) => OrchestratorResponse::success(
+            action.unwrap_or_else(|| "unknown".to_owned()),
+            out.detail,
+        ),
+        Err(e) => OrchestratorResponse::failure(action, e.to_string()),
     }
 }