chore(deps): upgrade eslint 7 → 8 and update related plugins

- eslint: ^7.5.0 → ^8.0.0 (resolves js-yaml@3 CVE via eslint dependency)
- eslint-config-react-app: ^6.0.0 → ^7.0.0 (required for eslint 8 compat)
- eslint-plugin-flowtype: ^5.2.0 → ^8.0.0 (v5 only supports eslint@7)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sserrata

package.json

@@ -50,10 +50,10 @@
     "babel-eslint": "^10.0.0",
     "cypress": "^8.7.0",
     "cypress-plugin-snapshots": "^1.4.4",
-    "eslint": "^7.5.0",
-    "eslint-config-react-app": "^6.0.0",
+    "eslint": "^8.0.0",
+    "eslint-config-react-app": "^7.0.0",
     "eslint-plugin-cypress": "^2.12.1",
-    "eslint-plugin-flowtype": "^5.2.0",
+    "eslint-plugin-flowtype": "^8.0.0",
     "eslint-plugin-header": "^3.1.1",
     "eslint-plugin-import": "^2.22.0",
     "eslint-plugin-jest": "^28.14.0",