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/process/parse-stdout.ts

@@ -0,0 +1,5 @@
+import type { TranscriptEntry } from "../types";
+
+export function parseProcessStdoutLine(line: string, ts: string): TranscriptEntry[] {
+  return [{ kind: "stdout", ts, text: line }];
+}