feat: initial SleepGuard implementation

Wake-on-demand proxy + agent system with SvelteKit dashboard.
Monorepo: shared types, proxy (Hono + http-proxy), agent (monitors + locks), web (SvelteKit SPA).

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

packages/proxy/web/src/lib/components/IdleTimer.svelte

@@ -0,0 +1,53 @@
+<script lang="ts">
+  interface Props {
+    lastActivity: string;
+    remainingSeconds: number;
+  }
+
+  let { lastActivity, remainingSeconds }: Props = $props();
+
+  function formatTime(seconds: number): string {
+    const m = Math.floor(seconds / 60);
+    const s = seconds % 60;
+    return `${m}:${String(s).padStart(2, '0')}`;
+  }
+
+  function formatDate(iso: string): string {
+    return new Date(iso).toLocaleTimeString();
+  }
+</script>
+
+<div class="card">
+  <h2>Idle Timer</h2>
+  <div class="timer-display">
+    <span class="time">{formatTime(remainingSeconds)}</span>
+    <span class="label">until idle check</span>
+  </div>
+  <p class="last-activity">Last activity: {formatDate(lastActivity)}</p>
+</div>
+
+<style>
+  .timer-display {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    gap: 0.25rem;
+  }
+  .time {
+    font-size: 2rem;
+    font-weight: 700;
+    font-variant-numeric: tabular-nums;
+  }
+  .label {
+    font-size: 0.75rem;
+    color: var(--text-muted);
+    text-transform: uppercase;
+    letter-spacing: 0.05em;
+  }
+  .last-activity {
+    margin-top: 0.75rem;
+    font-size: 0.8rem;
+    color: var(--text-dim);
+    text-align: center;
+  }
+</style>