fix(email): use automatic JSX runtime so templates render under tsx

Templates import no React (react-email convention); tsx resolves each
file's nearest tsconfig, so jsx:preserve made esbuild emit classic
React.createElement and background email rendering threw
'React is not defined'.

Claude-Session: https://claude.ai/code/session_012Bnvt1MghwHj4qQRxuQUGa

packages/email/tsconfig.json

@@ -1,7 +1,7 @@
 {
 	"extends": "@reactive-resume/config/tsconfig.base.json",
 	"compilerOptions": {
-		"jsx": "preserve",
+		"jsx": "react-jsx",
 		"lib": ["ESNext", "DOM"]
 	}
 }