Fix CI: cargo fmt and clippy -D warnings failures

- cargo fmt: reformat a match arm in app.rs and drop trailing blank
  lines the dx-components generator left in two mod.rs files
- clippy -D warnings (feedsignal-web, server feature): the generated
  ButtonVariant/ButtonSize enums have variants this app doesn't use yet
  (they're part of the component library's API surface, not dead code
  in the ordinary sense) — clippy's dead_code lint was failing the
  build under -D warnings, fixed with a scoped #[allow(dead_code)]

Verified all three CI jobs locally: cargo fmt --check, clippy for
native crates + both feedsignal-web feature sets, cargo test
--workspace --exclude feedsignal-web, and cargo audit.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XJJQb2DWZZwQ1yPiaAQQoY

crates/web/src/app.rs

@@ -60,7 +60,9 @@ fn SubscribeForm(on_subscribed: EventHandler<()>) -> Element {
             status.set(None);
             match subscribe_feed(feed_url).await {
                 Ok(count) => {
-                    status.set(Some(Ok(format!("Subscribed — pulled in {count} article(s)."))));
+                    status.set(Some(Ok(format!(
+                        "Subscribed — pulled in {count} article(s)."
+                    ))));
                     url.set(String::new());
                     on_subscribed.call(());
                 }

crates/web/src/components/button/component.rs

@@ -5,6 +5,11 @@ use dioxus_primitives::merge_attributes;
 #[css_module("/src/components/button/style.css")]
 struct Styles;
 
+// Variants beyond the ones this app currently uses are part of the
+// component library's public API, not unused code — CI runs clippy with
+// `-D warnings`, which would otherwise turn this dead_code lint into a
+// build failure.
+#[allow(dead_code)]
 #[derive(Copy, Clone, PartialEq, Default)]
 #[non_exhaustive]
 pub enum ButtonVariant {
@@ -30,6 +35,7 @@ impl ButtonVariant {
     }
 }
 
+#[allow(dead_code)]
 #[derive(Copy, Clone, PartialEq, Default)]
 #[non_exhaustive]
 pub enum ButtonSize {