chore: normalize tsconfig.json line endings (file missed by prior commit)

The earlier renormalize commit (771c845) missed frontend/tsconfig.json; this
completes the LF normalization so all tracked text files are LF. .gitattributes
(* text=auto eol=lf) prevents future CRLF.

frontend/tsconfig.json

@@ -1,26 +1,26 @@
-{␍
-  "compilerOptions": {␍
-    "target": "ES2020",␍
-    "useDefineForClassFields": true,␍
-    "lib": ["ES2020", "DOM", "DOM.Iterable"],␍
-    "module": "ESNext",␍
-    "skipLibCheck": true,␍
-    "moduleResolution": "bundler",␍
-    "allowImportingTsExtensions": true,␍
-    "resolveJsonModule": true,␍
-    "isolatedModules": true,␍
-    "noEmit": true,␍
-    "jsx": "react-jsx",␍
-    "strict": true,␍
-    "noImplicitAny": false,␍
-    "noUnusedLocals": false,␍
-    "noUnusedParameters": false,␍
-    "noFallthroughCasesInSwitch": true,␍
-    "baseUrl": ".",␍
-    "paths": {␍
-      "@/*": ["src/*"]␍
-    }␍
-  },␍
-  "include": ["src"],␍
-  "references": [{ "path": "./tsconfig.node.json" }]␍
-}␍
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "useDefineForClassFields": true,
+    "lib": ["ES2020", "DOM", "DOM.Iterable"],
+    "module": "ESNext",
+    "skipLibCheck": true,
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "jsx": "react-jsx",
+    "strict": true,
+    "noImplicitAny": false,
+    "noUnusedLocals": false,
+    "noUnusedParameters": false,
+    "noFallthroughCasesInSwitch": true,
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["src/*"]
+    }
+  },
+  "include": ["src"],
+  "references": [{ "path": "./tsconfig.node.json" }]
+}