Upgrade to React 19 and add Ontario Design System component specs

React 19 upgrade:
- Root and component-lab devDeps: react/react-dom ^19.2.4, @types/react/react-dom ^19.0.0
- component-lab: bring @vitejs/plugin-react and vite in line with root (v6, v8)
- Fix useUniqueId test regex: React 19 changed useId output from ":rN:"
  (stripped to "rN") to "_r_N_"; update pattern to match both formats

Ontario Design System specs (packages/react-ontario/src/components/):
- SPEC.md for all 10 Phase 1 components: OntarioButton, OntarioInput,
  OntarioHeader, OntarioFooter, OntarioPageAlert, OntarioCriticalAlert,
  OntarioCallout, OntarioAccordion, OntarioTable, OntarioCheckboxes
- Each spec covers: user story, domain subcomponents, full prop table,
  rendering/variant/security/event/accessibility task lists with named tests
- Security decisions documented per component: which props need safeHtml(),
  which need sanitizeHref(), which are pass-through only

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

Author: sschupbach-salesforce

apps/component-lab/package.json

@@ -12,17 +12,17 @@
     "@sfgps-ds/react-uswds": "*",
     "@uswds/uswds": "3.13.0",
     "dompurify": "^3.0.0",
-    "react": "^18.0.0",
-    "react-dom": "^18.0.0",
+    "react": "^19.2.4",
+    "react-dom": "^19.2.4",
     "react-router-dom": "^7.0.0"
   },
   "devDependencies": {
     "@types/dompurify": "^3.0.5",
     "@types/node": "^24.0.0",
-    "@types/react": "^18.0.0",
-    "@types/react-dom": "^18.0.0",
-    "@vitejs/plugin-react": "^4.0.0",
-    "typescript": "~5.5.0",
-    "vite": "^5.0.0"
+    "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
+    "@vitejs/plugin-react": "^6.0.0",
+    "typescript": "~5.8.0",
+    "vite": "^8.0.0"
   }
 }