chore: drop superseded admin-panel agent-config prototype after rebase onto main

main now ships the canonical org-scoped agent-config implementation
(OrganizationAgentRole/OrganizationAgentSkill + hub/src/agent/configuration.ts
+ hub/src/agent/skillStore.ts per ADR-0018, and envelope-encrypted
OrganizationProviderConnection per ADR-0024). The earlier admin-panel
prototype (OrgModel/OrgRole/simple ProviderConnection baseUrl+authToken,
modelRoutes.ts, agentConfig.ts, migration 20260710120000, admin-web
models/roles pages) is superseded and clashes with main's schema; drop it.

Follow-up still needed: rewire admin-web SPA to the new config APIs
(+layout.svelte nav still lists models/roles, RoleCard.svelte unused).

hub/src/admin/routes/orgRoutes.ts

@@ -12,7 +12,6 @@ import {
 import { registerAccessRoutes } from "./accessRoutes.js";
 import { registerExplorerRoutes } from "./explorerRoutes.js";
 import { registerMembersRoutes } from "./membersRoutes.js";
-import { registerModelRoutes } from "./modelRoutes.js";
 import { registerSessionsAndUsageRoutes } from "./sessionsRoutes.js";
 import { registerTeamsRoutes } from "./teamsRoutes.js";
 import { registerProviderConnectionRoutes } from "./providerConnectionRoutes.js";
@@ -106,10 +105,6 @@ export async function registerOrgRoutes(app: FastifyInstance, config: OrgRouteCo
     prisma: config.prisma,
     sessionSecret: config.sessionSecret,
   });
-  await registerModelRoutes(app, {
-    prisma: config.prisma,
-    sessionSecret: config.sessionSecret,
-  });
   await registerSessionsAndUsageRoutes(app, {
     prisma: config.prisma,
     sessionSecret: config.sessionSecret,