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>

frontend/src/features/agents/useAgents.ts

@@ -10,7 +10,7 @@
 import { useCallback, useEffect, useState } from "react";
 
 import type { Agent, AgentProfile, GatewayError } from "@/domain";
-import type { OpenTerminalOptions, TerminalHandle } from "@/ports";
+import type { LiveAgent, OpenTerminalOptions, TerminalHandle } from "@/ports";
 import { useGateways } from "@/app/di";
 
 /** What the agents UI needs from this hook. */
@@ -23,6 +23,8 @@ export interface AgentsViewModel {
   context: string;
   /** Profiles available for assigning to a new agent. */
   profiles: AgentProfile[];
+  /** Agents that currently own a live PTY session, as tracked by IdeA. */
+  liveAgents: LiveAgent[];
   /** Last error message, or `null`. */
   error: string | null;
   /** Whether a request is in flight. */
@@ -34,6 +36,8 @@ export interface AgentsViewModel {
   runningAgentId: string | null;
   /** Reloads the agent list. */
   refresh: () => Promise<void>;
+  /** Reloads the currently-live agent sessions. */
+  refreshLiveAgents: () => Promise<void>;
   /** Creates a new agent and refreshes the list. */
   createAgent: (name: string, profileId: string, initialContent?: string) => Promise<void>;
   /** Selects an agent and loads its context. */
@@ -52,8 +56,8 @@ export interface AgentsViewModel {
     options: OpenTerminalOptions,
     onData: (bytes: Uint8Array) => void,
   ) => Promise<TerminalHandle>;
-  /** Clears `runningAgentId` (called by the Stop button to unmount the terminal). */
-  stopAgent: () => void;
+  /** Stops an agent PTY explicitly by closing its live session id. */
+  stopAgent: (agentId?: string) => Promise<void>;
 }
 
 function describe(e: unknown): string {
@@ -64,12 +68,13 @@ function describe(e: unknown): string {
 }
 
 export function useAgents(projectId: string): AgentsViewModel {
-  const { agent, profile, system } = useGateways();
+  const { agent, profile, system, terminal } = useGateways();
 
   const [agents, setAgents] = useState<Agent[]>([]);
   const [selectedAgentId, setSelectedAgentId] = useState<string | null>(null);
   const [context, setContext] = useState<string>("");
   const [profiles, setProfiles] = useState<AgentProfile[]>([]);
+  const [liveAgents, setLiveAgents] = useState<LiveAgent[]>([]);
   const [error, setError] = useState<string | null>(null);
   const [busy, setBusy] = useState(false);
   const [runningAgentId, setRunningAgentId] = useState<string | null>(null);
@@ -91,10 +96,22 @@ export function useAgents(projectId: string): AgentsViewModel {
     }
   }, [agent, profile, projectId]);
 
+  const refreshLiveAgents = useCallback(async () => {
+    try {
+      setLiveAgents(await agent.listLiveAgents(projectId));
+    } catch {
+      setLiveAgents([]);
+    }
+  }, [agent, projectId]);
+
   useEffect(() => {
     void refresh();
   }, [refresh]);
 
+  useEffect(() => {
+    void refreshLiveAgents();
+  }, [refreshLiveAgents]);
+
   // Live refresh: the agents list is otherwise only reloaded on mount or after a
   // UI-driven CRUD. An agent created/launched/stopped *out of band* — most
   // notably by the orchestrator (`spawn_agent`, ARCHITECTURE §14.3) when an AI
@@ -109,6 +126,7 @@ export function useAgents(projectId: string): AgentsViewModel {
       .onDomainEvent((event) => {
         if (event.type === "agentLaunched" || event.type === "agentExited") {
           void refresh();
+          void refreshLiveAgents();
         }
       })
       .then((un) => {
@@ -119,7 +137,7 @@ export function useAgents(projectId: string): AgentsViewModel {
       cancelled = true;
       unsubscribe?.();
     };
-  }, [system, refresh]);
+  }, [system, refresh, refreshLiveAgents]);
 
   const createAgent = useCallback(
     async (name: string, profileId: string, initialContent?: string) => {
@@ -205,28 +223,51 @@ export function useAgents(projectId: string): AgentsViewModel {
       try {
         const handle = await agent.launchAgent(projectId, agentId, options, onData);
         setRunningAgentId(agentId);
+        void refreshLiveAgents();
         return handle;
       } catch (e) {
         setError(describe(e));
         throw e;
       }
     },
-    [agent, projectId],
+    [agent, projectId, refreshLiveAgents],
   );
 
-  const stopAgent = useCallback(() => {
-    setRunningAgentId(null);
-  }, []);
+  const stopAgent = useCallback(
+    async (agentId?: string) => {
+      const targetAgentId = agentId ?? runningAgentId;
+      const live = targetAgentId
+        ? liveAgents.find((candidate) => candidate.agentId === targetAgentId)
+        : null;
+      setRunningAgentId((current) =>
+        current === targetAgentId || !targetAgentId ? null : current,
+      );
+      if (live?.sessionId) {
+        try {
+          await terminal?.closeTerminal(live.sessionId);
+          setLiveAgents((current) =>
+            current.filter((candidate) => candidate.agentId !== targetAgentId),
+          );
+        } catch (e) {
+          setError(describe(e));
+          await refreshLiveAgents();
+        }
+      }
+    },
+    [liveAgents, refreshLiveAgents, runningAgentId, terminal],
+  );
 
   return {
     agents,
     selectedAgentId,
     context,
     profiles,
+    liveAgents,
     error,
     busy,
     runningAgentId,
     refresh,
+    refreshLiveAgents,
     createAgent,
     selectAgent,
     saveContext,