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)
+  })
+})