refactor(v0): render todos through heml template

Remove the hand-written push_str renderer for the v0 todos view so the canonical beginner example uses its .heml template for the whole page path, including form validation targets, notices, and keyed rows.

req: examples/001

req: canonical_authoring/003

examples/v0/src/main.rs

@@ -123,31 +123,13 @@ impl IntoHandlerFailure for AppError {
     }
 }
 
+#[derive(Hemplate)]
 struct Todos {
     summary: String,
     notice: String,
     rows: Vec<TodoRow>,
 }
 
-impl Hemplate for Todos {
-    fn render_into(&self, buf: &mut String) -> Result<(), hemplate::error::HemplateError> {
-        use std::fmt::Write as _;
-
-        buf.push_str("<section data-hemx-root=\"todos\">\n  <form data-hemx-handle=\"add_todo\" data-hemx-form=\"new_todo\">\n    <label>New todo\n      <input name=\"title\" required=\"required\">\n    </label>\n    <button type=\"submit\">Add</button>\n    <p data-hemx-error-for=\"title\"></p>\n  </form>\n\n  <p data-hemx-error role=\"status\" hidden=\"hidden\"></p>\n\n  <p data-hemx-slot=\"summary\">");
-        write!(buf, "{}", hemplate::HtmlEscape(&self.summary))?;
-        buf.push_str("</p>\n  <p data-hemx-slot=\"notice\">");
-        write!(buf, "{}", hemplate::HtmlEscape(&self.notice))?;
-        buf.push_str("</p>\n\n  <ul data-hemx-slot=\"todo_row\">\n");
-        for row in &self.rows {
-            buf.push_str("    ");
-            row.render_into(buf)?;
-            buf.push('\n');
-        }
-        buf.push_str("  </ul>\n</section>\n");
-        Ok(())
-    }
-}
-
 #[derive(Hemplate)]
 #[hemplate = "partials"]
 struct TodoRow {