fix: resolve WebSocket failure and crypto.randomUUID crash on HTTP/LXC

- Replace crypto.randomUUID() with a polyfill (generateUUID) that falls
  back to crypto.getRandomValues or Math.random — fixes crash on HTTP
  non-secure contexts where randomUUID is unavailable
- Fix WebSocket URL hardcoding port 8000 — use window.location.host so
  connections go through Nginx proxy in Docker/LXC instead of bypassing it
- Add /api/v1/status/ws/ location block in nginx.conf with WebSocket
  upgrade headers (must precede /api/ to avoid missing Upgrade header)

frontend/src/utils/__tests__/uuid.test.ts

@@ -0,0 +1,26 @@
+import { describe, it, expect, vi, afterEach } from 'vitest'
+import { generateUUID } from '../uuid'
+
+const UUID_REGEX = /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i
+
+describe('generateUUID', () => {
+  afterEach(() => {
+    vi.restoreAllMocks()
+  })
+
+  it('returns a valid v4 UUID using crypto.randomUUID when available', () => {
+    const id = generateUUID()
+    expect(id).toMatch(UUID_REGEX)
+  })
+
+  it('returns a valid v4 UUID using crypto.getRandomValues fallback', () => {
+    vi.spyOn(crypto, 'randomUUID' as never).mockImplementation(undefined as never)
+    const id = generateUUID()
+    expect(id).toMatch(UUID_REGEX)
+  })
+
+  it('generates unique IDs', () => {
+    const ids = new Set(Array.from({ length: 100 }, () => generateUUID()))
+    expect(ids.size).toBe(100)
+  })
+})

frontend/src/utils/uuid.ts

@@ -0,0 +1,25 @@
+/**
+ * Generates a UUID v4.
+ * Falls back to a manual implementation when crypto.randomUUID is unavailable
+ * (HTTP non-secure contexts, older browsers).
+ */
+export function generateUUID(): string {
+  if (typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function') {
+    return crypto.randomUUID()
+  }
+  // Fallback: RFC 4122 v4 UUID using crypto.getRandomValues if available
+  if (typeof crypto !== 'undefined' && typeof crypto.getRandomValues === 'function') {
+    const bytes = new Uint8Array(16)
+    crypto.getRandomValues(bytes)
+    bytes[6] = (bytes[6] & 0x0f) | 0x40
+    bytes[8] = (bytes[8] & 0x3f) | 0x80
+    return [...bytes]
+      .map((b, i) => ([4, 6, 8, 10].includes(i) ? '-' : '') + b.toString(16).padStart(2, '0'))
+      .join('')
+  }
+  // Last resort: Math.random based (not cryptographically secure)
+  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
+    const r = (Math.random() * 16) | 0
+    return (c === 'x' ? r : (r & 0x3) | 0x8).toString(16)
+  })
+}