feat: add process details, notifications, export, multi-host support

- Add per-process details modal with kill/pause/resume functionality
  - GET /api/v1/processes/:pid for detailed process info
  - POST /api/v1/processes/:pid/signal for sending signals
  - ProcessDetailModal component with state, resources, command line

- Add desktop notifications for alerts
  - Browser Notification API integration
  - Toggle in AlertsCard with permission handling
  - Auto-close for warnings, persistent for critical

- Add CSV/JSON export functionality
  - GET /api/v1/export/metrics?format=csv|json
  - Export buttons in SettingsPanel
  - Includes host name in filename

- Add multi-host monitoring support
  - HostSelector component for switching between backends
  - Hosts store with localStorage persistence
  - All API calls updated for remote host URLs

- Add disk I/O rate charts to HistoryCard
  - Read/write bytes/sec sparklines
  - Complements existing network rate charts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/lib/api/processes.ts

@@ -0,0 +1,39 @@
+import { get } from 'svelte/store';
+import { activeHost } from '$lib/stores/hosts';
+import type { ProcessDetail } from '$lib/types/metrics';
+
+function getApiBase(): string {
+	const host = get(activeHost);
+	const baseUrl = host.isLocal ? '' : host.url;
+	return `${baseUrl}/api/v1`;
+}
+
+export async function getProcessDetail(pid: number): Promise<ProcessDetail> {
+	const response = await fetch(`${getApiBase()}/processes/${pid}`);
+	if (!response.ok) {
+		throw new Error(`Failed to fetch process ${pid}: ${response.statusText}`);
+	}
+	return response.json();
+}
+
+export interface SignalResult {
+	success: boolean;
+	message: string;
+}
+
+export async function sendSignal(pid: number, signal: number): Promise<SignalResult> {
+	const response = await fetch(`${getApiBase()}/processes/${pid}/signal`, {
+		method: 'POST',
+		headers: { 'Content-Type': 'application/json' },
+		body: JSON.stringify({ signal })
+	});
+	return response.json();
+}
+
+// Common signal constants
+export const SIGNALS = {
+	SIGTERM: 15, // Graceful termination
+	SIGKILL: 9,  // Force kill
+	SIGSTOP: 19, // Pause process
+	SIGCONT: 18  // Resume process
+} as const;