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>

cli/src/adapters/http/format-event.ts

@@ -0,0 +1,4 @@
+export function printHttpStdoutEvent(raw: string, _debug: boolean): void {
+  const line = raw.trim();
+  if (line) console.log(line);
+}

cli/src/adapters/http/index.ts

@@ -0,0 +1,7 @@
+import type { CLIAdapterModule } from "../types.js";
+import { printHttpStdoutEvent } from "./format-event.js";
+
+export const httpCLIAdapter: CLIAdapterModule = {
+  type: "http",
+  formatStdoutEvent: printHttpStdoutEvent,
+};