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() {

slhx-derive/tests/surface.rs

@@ -1,4 +1,9 @@
-use slhx_derive::surface;
+use slhx_derive::{component, surface};
+
+#[component]
+mod local_component {
+    pub const EXISTING: u8 = 1;
+}
 
 #[surface]
 mod ui {
@@ -9,3 +14,8 @@ mod ui {
 fn surface_macro_preserves_inline_module_with_generated_file() {
     assert_eq!(ui::EXISTING, 1);
 }
+
+#[test]
+fn component_macro_preserves_inline_module_without_generated_symbols() {
+    assert_eq!(local_component::EXISTING, 1);
+}