feat(memory): embedders vectoriels réels HTTP + ONNX derrière features (LOT C1)

Remplace les StubEmbedder pour les stratégies localServer/api/localOnnx par de
vrais moteurs, chacun derrière une feature cargo off-by-default — la posture
fondatrice « rien d'imposé, zéro dépendance » (défaut none → rappel naïf) reste
byte-for-byte inchangée.

C1a (feature vector-http, reqwest rustls optional):
- HttpEmbedder couvrant localServer (Ollama/llama.cpp) et api (OpenAI/Voyage…),
  payload OpenAI-compatible /v1/embeddings, ordre restauré par index, bearer
  token lu via env var (jamais en clair), timeout client 30s.
- detect_ollama() pour la détection de l'existant (C3).

C1b (feature vector-onnx, fastembed v5 optional):
- OnnxEmbedder en-process (e5-small, dim 384), init paresseuse + spawn_blocking,
  cache modèle sous <app_data>/embedders/onnx — aucun download au build ni au
  first-run, uniquement à la demande au 1er embed.
- Catalogue RECOMMENDED_ONNX_MODELS + ONNX_CACHE_SUBDIR + onnx_model_is_cached
  exposés (sans feature) pour la config (C2) et la popup (C3).

embedder_from_profile(profile, onnx_cache_dir) dispatche feature-gated ; sans la
feature, retombe sur StubEmbedder (Unsupported) → fallback naïf via
AdaptiveMemoryRecall. Composition root (build_memory_recall) propage le cache dir.

Tests: 10 HTTP + 6 ONNX (dont 2 #[ignore] download réel) + 26 vectoriels, verts
en défaut, --features vector-http et --features vector-onnx.

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

crates/app-tauri/Cargo.toml

@@ -31,6 +31,12 @@ serde_json = { workspace = true }
 thiserror = { workspace = true }
 uuid = { workspace = true }
 
+[features]
+# Passthrough toggles to enable the real embedders in an IDE build. OFF by default
+# (founding posture: `none` ⇒ naïve recall, zero dependency).
+vector-http = ["infrastructure/vector-http"]
+vector-onnx = ["infrastructure/vector-onnx"]
+
 [dev-dependencies]
 uuid = { workspace = true }
 async-trait = { workspace = true }

crates/app-tauri/src/state.rs

@@ -35,7 +35,7 @@ use infrastructure::{
     FsEmbedderProfileStore, FsMemoryStore, FsOrchestratorWatcher, FsProfileStore, FsProjectStore,
     FsSkillStore, FsTemplateStore, Git2Repository, IdeaiContextStore, LocalFileSystem,
     LocalProcessSpawner, NaiveMemoryRecall, OrchestratorWatchHandle, PortablePtyAdapter,
-    SystemClock, TokioBroadcastEventBus, UuidGenerator, VectorMemoryRecall,
+    SystemClock, TokioBroadcastEventBus, UuidGenerator, VectorMemoryRecall, ONNX_CACHE_SUBDIR,
 };
 
 use crate::pty::PtyBridge;
@@ -393,10 +393,12 @@ impl AppState {
             .flatten()
         })
         .unwrap_or_else(EmbedderProfile::none);
+        let onnx_cache_dir = app_data_dir.join(ONNX_CACHE_SUBDIR);
         let memory_recall_port = build_memory_recall(
             Arc::clone(&fs_port),
             Arc::clone(&memory_store_port),
             &embedder_profile,
+            &onnx_cache_dir,
         );
 
         let create_agent = Arc::new(CreateAgentFromScratch::new(
@@ -711,9 +713,10 @@ pub(crate) fn build_memory_recall(
     fs: Arc<dyn FileSystem>,
     store: Arc<dyn MemoryStore>,
     profile: &EmbedderProfile,
+    onnx_cache_dir: &std::path::Path,
 ) -> Arc<dyn MemoryRecall> {
     let naive = Arc::new(NaiveMemoryRecall::new(Arc::clone(&store))) as Arc<dyn MemoryRecall>;
-    match embedder_from_profile(profile) {
+    match embedder_from_profile(profile, onnx_cache_dir) {
         None => naive,
         Some(embedder) => {
             let embedder: Arc<dyn Embedder> = Arc::from(embedder);
@@ -839,7 +842,12 @@ mod tests {
     async fn build_memory_recall_none_profile_matches_naive_recall() {
         let (fs, store) = seed_store().await;
 
-        let wired = build_memory_recall(Arc::clone(&fs), Arc::clone(&store), &EmbedderProfile::none());
+        let wired = build_memory_recall(
+            Arc::clone(&fs),
+            Arc::clone(&store),
+            &EmbedderProfile::none(),
+            std::path::Path::new("/unused-onnx-cache"),
+        );
         let naive = NaiveMemoryRecall::new(Arc::clone(&store));
 
         // 0 ⇒ empty; mid budgets ⇒ partial truncation; huge ⇒ full index order.