fix: add missing direct devDependencies to package.json

This is a prerequisite for CI to work with pnpm --frozen-lockfile.

Missing direct devDependencies that were only available transitively:
- eslint (lint script needs it)
- typescript (tsc script needs it)
- vite (provides vite/client.d.ts type definitions)
- vite-plugin-svgr (provides vite-plugin-svgr/client.d.ts type definitions)

Also fixed: tsconfig.json was missing skipLibCheck: true which caused
errors when type definitions referenced packages not in node_modules.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

package.json

@@ -35,6 +35,8 @@
     "react-dom": "^18.3.1",
     "react-router-dom": "^5.3.0",
     "typescript": "^5.6.2",
+    "vite": "^6.4.1",
+    "vite-plugin-svgr": "^4.5.0",
     "vitest": "^3.0.5"
   }
 }