Use React's "automatic" runtime instead of "classic"

- https://legacy.reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html
- https://swc.rs/docs/configuration/compilation#jsctransformreactruntime

> "Use `runtime: automatic` to use a JSX runtime module
  (e.g. `react/jsx-runtime` introduced in React 17)."

(Note that with the new jsx transform, you can now use jsx/tsx in a file
without importing React. TS knows this now, too. Feel free to take its
suggestion.)

(The $schema key added to .swcrc just adds better hints when editing the
JSON config, it's unrelated to the runtime change.)

.swcrc

@@ -1,4 +1,5 @@
 {
+  "$schema": "https://swc.rs/schema.json",
   "sourceMaps": true,
   "jsc": {
     "parser": {
@@ -7,7 +8,7 @@
     },
     "transform": {
       "react": {
-        "runtime": "classic",
+        "runtime": "automatic",
         "refresh": true
       }
     }

tsconfig.json

@@ -25,7 +25,7 @@
     "skipLibCheck": true,
     "allowJs": true,
     "outDir": "out",
-    "jsx": "react",
+    "jsx": "react-jsx",
     "plugins": [{ "name": "typescript-plugin-css-modules"}]
   },
   "include": [