feat(slhx): prefer render methods for views

Move view rendering onto Slot::render and KeyedSlot append/prepend/replace extension methods, leaving explicit text/html methods for non-view escape hatches.

req: codegen/002

req: view/001

slhx-test/tests/inspector.rs

@@ -21,7 +21,7 @@ fn inspects_tuple_effects() {
 #[test]
 fn finds_keyed_slot_targets() {
     let rows = KeyedSlot::<u32, String>::new(9);
-    let inspected = slhx_test::inspect(rows.append(7, String::from("row")));
+    let inspected = slhx_test::inspect(rows.append_text(7, String::from("row")));
 
     assert!(inspected.has_keyed_slot(rows));
     assert_eq!(inspected.ops().len(), 1);