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/store/profile.rs

@@ -23,7 +23,7 @@ use async_trait::async_trait;
 use serde::{Deserialize, Serialize};
 
 use domain::ids::ProfileId;
-use domain::ports::{FileSystem, ProfileStore, RemotePath, StoreError};
+use domain::ports::{EmbedderProfileStore, FileSystem, ProfileStore, RemotePath, StoreError};
 use domain::profile::{AgentProfile, EmbedderProfile};
 
 /// File name of the profiles store inside the app-data dir.
@@ -181,10 +181,11 @@ impl Default for EmbedderDoc {
 /// calqué on [`FsProfileStore`]: `embedder.json` in the global IDE app-data dir,
 /// mirroring `profiles.json`.
 ///
-/// No domain `EmbedderProfileStore` port exists yet — embedder profiles are pure
-/// configuration loaded at the composition root, so this is a concrete loader. A
-/// dedicated port (parallel to [`ProfileStore`]) is an easy follow-up the day the
-/// UI needs CRUD over embedder profiles.
+/// Implements the domain [`EmbedderProfileStore`] port (parallel to [`ProfileStore`]).
+/// The inherent `list`/`save`/`delete` methods are kept so the composition root can
+/// load the configured profile *before* type-erasing to `Arc<dyn EmbedderProfileStore>`
+/// (e.g. inside a one-shot blocking runtime in `state.rs`); the trait impl simply
+/// delegates to them.
 ///
 /// Cheap to clone (everything behind `Arc`).
 #[derive(Clone)]
@@ -270,3 +271,18 @@ impl FsEmbedderProfileStore {
         self.write_doc(&doc).await
     }
 }
+
+#[async_trait]
+impl EmbedderProfileStore for FsEmbedderProfileStore {
+    async fn list(&self) -> Result<Vec<EmbedderProfile>, StoreError> {
+        FsEmbedderProfileStore::list(self).await
+    }
+
+    async fn save(&self, profile: &EmbedderProfile) -> Result<(), StoreError> {
+        FsEmbedderProfileStore::save(self, profile).await
+    }
+
+    async fn delete(&self, id: &str) -> Result<(), StoreError> {
+        FsEmbedderProfileStore::delete(self, id).await
+    }
+}