fix: resolve npm vulnerabilities and flaky Performance test (opensearch-project#93)

- Update docs dependencies to fix npm audit vulnerabilities
- Fix flaky property-based test: alt text generator could produce empty
  strings after sanitizing special characters (e.g. "<>&" → ""), causing
  `expect(altText).toBeTruthy()` to fail non-deterministically

Signed-off-by: Vamsi Manohar <reddyvam@amazon.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: vamsimanohar

docs/package-lock.json

@@ -29,6 +29,10 @@
     "shiki": "^3.21.0",
     "tailwindcss": "^4.1.18"
   },
+  "overrides": {
+    "yauzl": "^3.2.1",
+    "undici": "^7.24.0"
+  },
   "devDependencies": {
     "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.2",

docs/package.json

@@ -40,7 +40,7 @@ describe('Performance - Property 6: Below-fold images are lazy-loaded', () => {
                 fc.webUrl({ validSchemes: ['https'] })
               ),
               alt: fc.string({ minLength: 3, maxLength: 100 })
-                .map(s => s.replace(/[<>"'&]/g, '')), // Sanitize
+                .map(s => s.replace(/[<>"'&]/g, '') || 'image description'), // Sanitize with fallback
               isBelowFold: fc.boolean(),
               width: fc.option(fc.integer({ min: 50, max: 1000 })),
               height: fc.option(fc.integer({ min: 50, max: 1000 }))