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/app-tauri/src/events.rs

@@ -129,6 +129,21 @@ pub enum DomainEventDto {
         /// Project id.
         project_id: String,
     },
+    /// A project's memory crossed the recall budget while no embedder is configured
+    /// (LOT C3 — §14.5.5): a one-time, dismissible "configure an embedder?" hint.
+    #[serde(rename_all = "camelCase")]
+    EmbedderSuggested {
+        /// Project id.
+        project_id: String,
+        /// Whether a local Ollama-style embedding server was detected.
+        ollama_detected: bool,
+        /// Ids of recommended ONNX models already present in the local cache.
+        onnx_cached: Vec<String>,
+        /// Whether the HTTP capability is compiled in.
+        vector_http_enabled: bool,
+        /// Whether the in-process ONNX capability is compiled in.
+        vector_onnx_enabled: bool,
+    },
     /// Raw PTY output (normally routed to a per-session channel, not here).
     #[serde(rename_all = "camelCase")]
     PtyOutput {
@@ -163,11 +178,7 @@ impl From<&DomainEvent> for DomainEventDto {
                 template_id: template_id.to_string(),
                 version: version.get(),
             },
-            DomainEvent::AgentDriftDetected {
-                agent_id,
-                from,
-                to,
-            } => Self::AgentDriftDetected {
+            DomainEvent::AgentDriftDetected { agent_id, from, to } => Self::AgentDriftDetected {
                 agent_id: agent_id.to_string(),
                 from: from.get(),
                 to: to.get(),
@@ -212,6 +223,19 @@ impl From<&DomainEvent> for DomainEventDto {
             DomainEvent::MemoryIndexRebuilt { project_id } => Self::MemoryIndexRebuilt {
                 project_id: project_id.to_string(),
             },
+            DomainEvent::EmbedderSuggested {
+                project_id,
+                ollama_detected,
+                onnx_cached,
+                vector_http_enabled,
+                vector_onnx_enabled,
+            } => Self::EmbedderSuggested {
+                project_id: project_id.to_string(),
+                ollama_detected: *ollama_detected,
+                onnx_cached: onnx_cached.clone(),
+                vector_http_enabled: *vector_http_enabled,
+                vector_onnx_enabled: *vector_onnx_enabled,
+            },
             DomainEvent::PtyOutput { session_id, bytes } => Self::PtyOutput {
                 session_id: session_id.to_string(),
                 bytes: bytes.clone(),