feat(api): streamline generated app authoring

Move the canonical examples toward generated component-root helpers, typed form decoding, async/state handler registration, and derive-driven app/component registry wiring. Tighten requirements and diagnostics for the server-first, selectorless authoring path.

Verified with cargo run -p slhx-xtask -- test, cargo check --workspace, redgate list, redgate refs, redgate health --strict, and git diff --check.

req: canonical/001

req: canonical/003

req: canonical/004

req: dx/002

req: derive_app/001

req: component/003

req: form/004

req: axum_integration/003

examples/kanban/src/lib.rs

@@ -6,7 +6,7 @@ mod tests {
     use super::ui::{board, board_card};
     use hemplate::Hemplate;
     use scraper::{Html, Selector};
-    use slhx::{Effect, IntoEffect, Payload};
+    use slhx::IntoEffect;
     use slhx_test::inspect;
 
     #[derive(Hemplate)]
@@ -27,12 +27,11 @@ mod tests {
     #[test]
     fn kanban_board_updates_generated_slot() {
         fn render_board() -> impl IntoEffect {
-            board::targets::board.put(&empty_board())
+            board::board.put(&empty_board())
         }
 
         let effect = inspect(render_board());
-        assert!(effect.has_slot(board::slots::board));
-        assert!(matches!(effect.ops(), [Effect::Put { payload: Payload::Html(_), .. }]));
+        assert!(effect.updates_html(board::board));
     }
 
     // req: html_safety/002 req: view/001 req: test/005
@@ -45,7 +44,9 @@ mod tests {
 
     fn empty_board() -> BoardColumns {
         // req: html_safety/002 req: view/001
-        BoardColumns { columns: Vec::new() }
+        BoardColumns {
+            columns: Vec::new(),
+        }
     }
 
     fn selector(value: &str) -> Selector {
@@ -57,19 +58,21 @@ mod tests {
     fn kanban_form_handler_is_checked_against_hemplate_form() {
         #[slhx::handler]
         fn create_card(_form: slhx::Form<CreateCard>) -> impl IntoEffect {
-            board::slots::notice.text("queued")
+            board::notice.text("queued")
         }
 
         let effect = inspect(create_card(CreateCard::FORM));
 
-        assert!(effect.has_slot(board::slots::notice));
-        assert!(matches!(effect.ops(), [Effect::Put { payload: Payload::Text(_), .. }]));
+        assert!(effect.updates_text(board::notice));
     }
 
     // req: examples/001 req: form/002 req: codegen/003
     #[test]
     fn kanban_template_exports_form_and_card_handles() {
-        assert_ne!(board::handles::create_card.id(), board_card::handles::move_right.id());
-        assert_eq!(board::forms::create_card.field("title").resource, board::forms::create_card.id());
+        assert_ne!(board::create_card.id(), board_card::move_right.id());
+        assert_eq!(
+            board::create_card_form.field("title").resource,
+            board::create_card_form.id()
+        );
     }
 }