refactor(techdemo): scope card handles to partials

Move board card and lane actions onto their reusable partial templates, register the scoped generated handles directly, and remove hidden shell-level handle anchors and manual handle fields from the rendered view data.

req: component/003

req: view/001

req: examples/001

examples/techdemo/src/lib.rs

@@ -57,7 +57,7 @@ mod tests {
     fn techdemo_exports_form_and_interaction_handles() {
         assert_ne!(
             ui::control_center::handles::launch_work.id(),
-            ui::control_center::handles::advance_work.id()
+            ui::issue_card::handles::advance_work.id()
         );
         assert_eq!(
             ui::control_center::forms::launch_work.field("title").resource,