Upgrade React 18 → 19 and React Router 6 → 7

- react, react-dom: 18.3.1 → 19.2.3
- react-router-dom: 6.30.2 → 7.11.0

Note: react-ga doesn't officially support React 19 yet but works fine.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: bfirsh

.claude/settings.local.json

@@ -4,7 +4,8 @@
       "Bash(npm view:*)",
       "Bash(ls:*)",
       "Bash(npm run build:*)",
-      "Bash(npm test:*)"
+      "Bash(npm test:*)",
+      "Bash(npm ls:*)"
     ],
     "deny": []
   }

package-lock.json

@@ -9,10 +9,10 @@
     "jsnes": "git+ssh://git@github.com/bfirsh/jsnes.git",
     "prop-types": "^15.8.1",
     "raven-js": "^3.27.2",
-    "react": "^18.2.0",
-    "react-dom": "^18.2.0",
+    "react": "^19.2.3",
+    "react-dom": "^19.2.3",
     "react-ga": "^3.3.1",
-    "react-router-dom": "^6.3.0",
+    "react-router-dom": "^7.11.0",
     "reactstrap": "^9.1.3",
     "ringbufferjs": "^2.0.0",
     "sass": "^1.94.2"