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/http/config-fields.tsx

@@ -0,0 +1,38 @@
+import type { AdapterConfigFieldsProps } from "../types";
+import {
+  Field,
+  DraftInput,
+  help,
+} from "../../components/agent-config-primitives";
+
+const inputClass =
+  "w-full rounded-md border border-border px-2.5 py-1.5 bg-transparent outline-none text-sm font-mono placeholder:text-muted-foreground/40";
+
+export function HttpConfigFields({
+  isCreate,
+  values,
+  set,
+  config,
+  eff,
+  mark,
+}: AdapterConfigFieldsProps) {
+  return (
+    <Field label="Webhook URL" hint={help.webhookUrl}>
+      <DraftInput
+        value={
+          isCreate
+            ? values!.url
+            : eff("adapterConfig", "url", String(config.url ?? ""))
+        }
+        onCommit={(v) =>
+          isCreate
+            ? set!({ url: v })
+            : mark("adapterConfig", "url", v || undefined)
+        }
+        immediate
+        className={inputClass}
+        placeholder="https://..."
+      />
+    </Field>
+  );
+}