feat(model-server): frontend modèles locaux — badge de statut & CRUD serveurs (#35) et wizard multi-profils OpenCode (#36)

Sprint « Modeles locaux », couche frontend.

#35 :
- F35.1 badge de statut de lancement du serveur local
  (ModelServerLaunchBadge + useAgentsModelServer).
- F35.2 feature model-servers : CRUD (ModelServersPanel / useModelServers /
  gateway modelServer) et ModelServerSelect.

#36 :
- Liste multi-profils OpenCode dans le wizard de premier lancement,
  gateway de clonage (clone_opencode_profile_from_seed).

Tests verts (exécution réelle) : tsc propre, vitest 608/608.

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

frontend/src/features/model-servers/useModelServers.ts

@@ -0,0 +1,126 @@
+/**
+ * `useModelServers` — view-model for the local model server registry (F35.2).
+ * Owns the declared-servers list and the CRUD actions, consuming the
+ * {@link ModelServerGateway} exclusively (never `invoke()`), so the UI is
+ * testable with a mock.
+ *
+ * Delete surfaces the backend `model_server_in_use` rejection as a dedicated,
+ * human-readable message (a server still referenced by a profile cannot be
+ * removed).
+ */
+
+import { useCallback, useEffect, useState } from "react";
+
+import type { GatewayError, LocalModelServerConfig } from "@/domain";
+import { useGateways } from "@/app/di";
+
+/** What the model-server UI needs from this hook. */
+export interface ModelServersViewModel {
+  /** The declared local model servers. */
+  servers: LocalModelServerConfig[];
+  /** Last error message, or `null`. */
+  error: string | null;
+  /** Whether a request is in flight. */
+  busy: boolean;
+  /** Reloads the server list. */
+  reload: () => Promise<void>;
+  /** Creates or updates a server; returns the persisted config (or `null` on error). */
+  save: (config: LocalModelServerConfig) => Promise<LocalModelServerConfig | null>;
+  /** Deletes a server by id; returns `true` on success. */
+  remove: (serverId: string) => Promise<boolean>;
+  /** Clears the current error banner. */
+  clearError: () => void;
+}
+
+function describe(e: unknown): string {
+  if (e && typeof e === "object" && "message" in e) {
+    return String((e as GatewayError).message);
+  }
+  return String(e);
+}
+
+function codeOf(e: unknown): string | undefined {
+  if (e && typeof e === "object" && "code" in e) {
+    return String((e as GatewayError).code);
+  }
+  return undefined;
+}
+
+export function useModelServers(): ModelServersViewModel {
+  const { modelServer } = useGateways();
+  const [servers, setServers] = useState<LocalModelServerConfig[]>([]);
+  const [error, setError] = useState<string | null>(null);
+  const [busy, setBusy] = useState(false);
+
+  const reload = useCallback(async () => {
+    setBusy(true);
+    setError(null);
+    try {
+      setServers(await modelServer.listModelServers());
+    } catch (e) {
+      setError(describe(e));
+    } finally {
+      setBusy(false);
+    }
+  }, [modelServer]);
+
+  useEffect(() => {
+    void reload();
+  }, [reload]);
+
+  const save = useCallback(
+    async (config: LocalModelServerConfig) => {
+      setBusy(true);
+      setError(null);
+      try {
+        const saved = await modelServer.saveModelServer(config);
+        setServers((prev) => {
+          const i = prev.findIndex((s) => s.id === saved.id);
+          if (i >= 0) {
+            const next = prev.slice();
+            next[i] = saved;
+            return next;
+          }
+          return [...prev, saved];
+        });
+        return saved;
+      } catch (e) {
+        setError(describe(e));
+        return null;
+      } finally {
+        setBusy(false);
+      }
+    },
+    [modelServer],
+  );
+
+  const remove = useCallback(
+    async (serverId: string) => {
+      setBusy(true);
+      setError(null);
+      try {
+        await modelServer.deleteModelServer(serverId);
+        setServers((prev) => prev.filter((s) => s.id !== serverId));
+        return true;
+      } catch (e) {
+        // A referenced server cannot be deleted — turn the stable backend code
+        // into an actionable message rather than a raw error string.
+        if (codeOf(e) === "model_server_in_use") {
+          setError(
+            "Ce serveur est encore utilisé par un profil : détache-le d'abord (choisis « aucun » ou un autre serveur) avant de le supprimer.",
+          );
+        } else {
+          setError(describe(e));
+        }
+        return false;
+      } finally {
+        setBusy(false);
+      }
+    },
+    [modelServer],
+  );
+
+  const clearError = useCallback(() => setError(null), []);
+
+  return { servers, error, busy, reload, save, remove, clearError };
+}