feat(systemd): unit overview + journal viewer pages

- Add journalctl_recent command and scrum4me-web to whitelist in commands.yml.example
- Add SYSTEMD_UNITS env var to .env.example
- lib/parse-systemd.ts: parse activeState, subState, uptime, description
- /app/systemd: server page reading SYSTEMD_UNITS, client list with 10s polling and status badges
- /app/systemd/[unit]: server detail page, client component showing systemctl status + last 100 journal lines (polling 10s)

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

app/systemd/[unit]/page.tsx

@@ -0,0 +1,78 @@
+import Link from 'next/link'
+import { redirect } from 'next/navigation'
+import { getCurrentUser } from '@/lib/session'
+import { execAgent } from '@/lib/agent-client'
+import UnitDetail from './_components/unit-detail'
+
+export const dynamic = 'force-dynamic'
+
+type Props = {
+  params: Promise<{ unit: string }>
+}
+
+function getAllowedUnits(): string[] {
+  return (process.env.SYSTEMD_UNITS ?? '')
+    .split(',')
+    .map((u) => u.trim())
+    .filter(Boolean)
+}
+
+export default async function SystemdUnitPage({ params }: Props) {
+  const user = await getCurrentUser()
+  if (!user) redirect('/login')
+
+  const { unit } = await params
+  const unitName = decodeURIComponent(unit)
+
+  if (!getAllowedUnits().includes(unitName)) {
+    return (
+      <div className="min-h-screen bg-background p-6">
+        <div className="mx-auto max-w-6xl space-y-6">
+          <div className="flex items-center gap-3">
+            <Link href="/systemd" className="text-sm text-muted-foreground hover:text-foreground">
+              ← systemd Units
+            </Link>
+          </div>
+          <div className="rounded-lg border border-destructive/30 bg-destructive/10 px-4 py-3 text-sm text-destructive">
+            Unit &quot;{unitName}&quot; not found in SYSTEMD_UNITS.
+          </div>
+        </div>
+      </div>
+    )
+  }
+
+  let initialStatusOutput = ''
+  let initialJournalOutput = ''
+  let initialError: string | null = null
+
+  try {
+    const [statusOut, journalOut] = await Promise.all([
+      execAgent('systemctl_status', [unitName]),
+      execAgent('journalctl_recent', [unitName]),
+    ])
+    initialStatusOutput = statusOut
+    initialJournalOutput = journalOut
+  } catch (err) {
+    initialError = err instanceof Error ? err.message : 'Failed to fetch unit data'
+  }
+
+  return (
+    <div className="min-h-screen bg-background p-6">
+      <div className="mx-auto max-w-6xl space-y-6">
+        <div className="flex items-center gap-3">
+          <Link href="/systemd" className="text-sm text-muted-foreground hover:text-foreground">
+            ← systemd Units
+          </Link>
+          <span className="text-muted-foreground">/</span>
+          <h1 className="text-2xl font-semibold tracking-tight font-mono">{unitName}</h1>
+        </div>
+        <UnitDetail
+          unitName={unitName}
+          initialStatusOutput={initialStatusOutput}
+          initialJournalOutput={initialJournalOutput}
+          initialError={initialError}
+        />
+      </div>
+    </div>
+  )
+}