chore: migrate to TypeScript

- Convert all .js files to .tsx/.ts
- Add types for data structures (MuseumRecord, Metrics, etc.)
- Add type declarations for react-chartjs-2
- Configure tsconfig with relaxed strictness for gradual adoption
- All components now use TypeScript

tsconfig.json

@@ -0,0 +1,22 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "lib": ["dom", "dom.iterable", "esnext"],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "allowSyntheticDefaultImports": true,
+    "strict": false,
+    "noImplicitAny": false,
+    "strictNullChecks": false,
+    "forceConsistentCasingInFileNames": true,
+    "noFallthroughCasesInSwitch": true,
+    "module": "esnext",
+    "moduleResolution": "node",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "jsx": "react-jsx"
+  },
+  "include": ["src"]
+}