fix(derive): keep components incremental

Let #[slhx::component] preserve inline modules when generated symbols are absent, while still enforcing handler completeness when slhx.syms exists.

req: component/005

req: test/002

slhx-derive/src/lib.rs

@@ -89,22 +89,10 @@ pub fn component(_attr: TokenStream, item: TokenStream) -> TokenStream {
         .into();
     };
     let Some(syms_path) = syms_path() else {
-        return quote!(
-            #module
-            compile_error!("#[slhx::component] requires OUT_DIR; run inside a Cargo crate with slhx_build::app() in build.rs");
-        )
-        .into();
+        return quote!(#module).into();
     };
     if !syms_path.exists() {
-        let message = format!(
-            "#[slhx::component] could not find {}; add slhx_build::app().run()? to build.rs or check template generation",
-            syms_path.display()
-        );
-        return quote!(
-            #module
-            compile_error!(#message);
-        )
-        .into();
+        return quote!(#module).into();
     }
     let missing = missing_component_handlers(&syms_path, items);
     if !missing.is_empty() {