refactor: replace the legacy function runtime with shared

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/compiler/src/codegen.ts

@@ -1310,9 +1310,7 @@ function hydrationAttribute(ast: PageAst): string {
 
 function targetFunctions(ast: PageAst, target: "browser" | "server"): string {
   const runtimes =
-    target === "browser"
-      ? (["legacy", "client", "shared"] as const)
-      : (["legacy", "server", "shared"] as const);
+    target === "browser" ? (["client", "shared"] as const) : (["server", "shared"] as const);
   return ast.functions
     .map((body) => stripRuntimeFunctionModifiers(body, [...runtimes]))
     .map((body) => body.trim())