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/application/src/memory/usecases.rs

@@ -136,7 +136,8 @@ impl UpdateMemory {
         let memory = Memory::new(frontmatter, MarkdownDoc::new(input.content))
             .map_err(|e| AppError::Invalid(e.to_string()))?;
         self.memories.save(&input.project_root, &memory).await?;
-        self.events.publish(DomainEvent::MemorySaved { slug: input.slug });
+        self.events
+            .publish(DomainEvent::MemorySaved { slug: input.slug });
         Ok(UpdateMemoryOutput { memory })
     }
 }
@@ -262,8 +263,11 @@ impl DeleteMemory {
     /// - [`AppError::NotFound`] if no note carries that slug,
     /// - [`AppError::Store`] on persistence failure.
     pub async fn execute(&self, input: DeleteMemoryInput) -> Result<(), AppError> {
-        self.memories.delete(&input.project_root, &input.slug).await?;
-        self.events.publish(DomainEvent::MemoryDeleted { slug: input.slug });
+        self.memories
+            .delete(&input.project_root, &input.slug)
+            .await?;
+        self.events
+            .publish(DomainEvent::MemoryDeleted { slug: input.slug });
         Ok(())
     }
 }