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/terminal/registry.rs

@@ -128,19 +128,21 @@ impl TerminalSessions {
         })
     }
 
-    /// Lists every currently-live agent and the cell hosting it.
+    /// Lists every currently-live agent, its current host cell and session id.
     ///
-    /// One `(AgentId, NodeId)` pair per session tagged [`SessionKind::Agent`].
+    /// One `(AgentId, NodeId, SessionId)` tuple per session tagged [`SessionKind::Agent`].
     /// Used by the `list_live_agents` query so the UI can disable an agent that
     /// is already running elsewhere (it cannot be launched in a second cell).
     #[must_use]
-    pub fn live_agents(&self) -> Vec<(AgentId, NodeId)> {
+    pub fn live_agents(&self) -> Vec<(AgentId, NodeId, SessionId)> {
         self.entries
             .lock()
             .map(|m| {
                 m.values()
                     .filter_map(|e| match e.session.kind {
-                        SessionKind::Agent { agent_id } => Some((agent_id, e.session.node_id)),
+                        SessionKind::Agent { agent_id } => {
+                            Some((agent_id, e.session.node_id, e.session.id))
+                        }
                         SessionKind::Plain => None,
                     })
                     .collect()
@@ -148,6 +150,28 @@ impl TerminalSessions {
             .unwrap_or_default()
     }
 
+    /// Rebinds a live agent session to a new visible layout node without
+    /// respawning the CLI process.
+    ///
+    /// This is the application-level "cell is a view" operation: closing a cell
+    /// can leave an agent running in the background, and later opening that agent
+    /// in another cell updates only the view binding (`node_id`). The PTY handle,
+    /// session id, scrollback and process stay untouched.
+    #[must_use]
+    pub fn rebind_agent_node(
+        &self,
+        agent_id: &AgentId,
+        node_id: NodeId,
+    ) -> Option<TerminalSession> {
+        self.entries.lock().ok().and_then(|mut m| {
+            let entry = m.values_mut().find(
+                |e| matches!(e.session.kind, SessionKind::Agent { agent_id: a } if &a == agent_id),
+            )?;
+            entry.session.node_id = node_id;
+            Some(entry.session.clone())
+        })
+    }
+
     /// Returns the [`PtyHandle`]s of every currently-registered session.
     ///
     /// Used at application shutdown to kill all live PTYs cleanly (the

crates/application/src/terminal/usecases.rs

@@ -67,10 +67,7 @@ impl OpenTerminal {
     /// # Errors
     /// - [`AppError::Invalid`] for a non-absolute cwd or a zero-sized terminal,
     /// - [`AppError::Process`] if the PTY fails to spawn.
-    pub async fn execute(
-        &self,
-        input: OpenTerminalInput,
-    ) -> Result<OpenTerminalOutput, AppError> {
+    pub async fn execute(&self, input: OpenTerminalInput) -> Result<OpenTerminalOutput, AppError> {
         let cwd = ProjectPath::new(input.cwd).map_err(|e| AppError::Invalid(e.to_string()))?;
         let size =
             PtySize::new(input.rows, input.cols).map_err(|e| AppError::Invalid(e.to_string()))?;