feat(build): generate slot target objects

Add generated targets::<slot> wrapper objects so partial swaps read as target.put/append/replace while preserving existing lower-aware commands and IntoEffect wiring.

req: dx/006

req: codegen/001

req: codegen/002

req: component/003

examples/techdemo/src/lib.rs

@@ -3,7 +3,7 @@ pub mod ui {}
 
 #[cfg(test)]
 mod tests {
-    use super::ui::control_center::{forms, handles, slots};
+    use super::ui::control_center::{forms, handles, slots, targets};
     use super::ui::issue_card::handles as card_handles;
     use super::ui::issue_lane::events as lane_events;
     use hemplate::Hemplate;
@@ -30,7 +30,7 @@ mod tests {
     fn techdemo_uses_generated_slots_for_multi_target_updates() {
         fn update() -> impl IntoEffect {
             (
-                super::ui::put(slots::hero_metrics, &FastMetric { label: "fast" }),
+                targets::hero_metrics.put(&FastMetric { label: "fast" }),
                 slots::notice.text("typed"),
             )
         }