feat(flows): add update_caddy_config flow with validate, reload/force-restart, and smoke test

- Update flows.example/update_caddy_config.yml with caddy_validate → caddy_reload → smoke test steps and hostname comments
- Add flows.example/update_caddy_config_force.yml for docker compose hard restart variant
- Add /flows/update-caddy-config UI page with reload/force-restart toggle, dry-run mode showing pending Caddyfile preview, hostname detection, and audit log link

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

app/flows/update-caddy-config/page.tsx

@@ -0,0 +1,36 @@
+import Link from 'next/link'
+import { redirect } from 'next/navigation'
+import { getCurrentUser } from '@/lib/session'
+import { execAgent } from '@/lib/agent-client'
+import FlowPanel from './_components/flow-panel'
+
+export const dynamic = 'force-dynamic'
+
+export default async function UpdateCaddyConfigPage() {
+  const user = await getCurrentUser()
+  if (!user) redirect('/login')
+
+  let caddyfile = ''
+  let caddyfileError: string | null = null
+  try {
+    caddyfile = await execAgent('caddy_show_config')
+  } catch (err) {
+    caddyfileError = err instanceof Error ? err.message : 'failed to load Caddyfile'
+  }
+
+  return (
+    <div className="min-h-screen bg-background p-6">
+      <div className="mx-auto max-w-4xl space-y-6">
+        <div className="flex items-center gap-3">
+          <Link href="/" className="text-sm text-muted-foreground hover:text-foreground">
+            ← Home
+          </Link>
+          <span className="text-muted-foreground">/</span>
+          <h1 className="text-2xl font-semibold tracking-tight">Update Caddy Config</h1>
+        </div>
+
+        <FlowPanel caddyfile={caddyfile} caddyfileError={caddyfileError} />
+      </div>
+    </div>
+  )
+}