Extract adapter registry across CLI, server, and UI

Refactor monolithic heartbeat service, AgentConfigForm, and CLI
heartbeat-run into a proper adapter registry pattern. Each adapter
type (process, claude-local, codex-local, http) gets its own module
with server-side execution logic, CLI invocation, and UI config form.
Significantly reduces file sizes and enables adding new adapters
without touching core code.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/adapters/registry.ts

@@ -0,0 +1,13 @@
+import type { UIAdapterModule } from "./types";
+import { claudeLocalUIAdapter } from "./claude-local";
+import { codexLocalUIAdapter } from "./codex-local";
+import { processUIAdapter } from "./process";
+import { httpUIAdapter } from "./http";
+
+const adaptersByType = new Map<string, UIAdapterModule>(
+  [claudeLocalUIAdapter, codexLocalUIAdapter, processUIAdapter, httpUIAdapter].map((a) => [a.type, a]),
+);
+
+export function getUIAdapter(type: string): UIAdapterModule {
+  return adaptersByType.get(type) ?? processUIAdapter;
+}