style(host): cargo fmt --all (rustfmt 1.9.0 drift)

The CI image's rustfmt reformats these files (multi-line assert!/tracing! macros,
match-arm and struct-variant wrapping) — pre-existing drift that the Format job caught.
Reformat to match. Pure formatting; no logic change. main.rs also gets a blank line
before a standalone comment so rustfmt stops mis-indenting it as a trailing-comment
continuation.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/punktfunk-host/src/gamestream/apps.rs

@@ -274,7 +274,10 @@ mod tests {
         );
         // No pretty-print newlines anywhere in the element stream, and no whitespace-only text
         // nodes between any adjacent tags.
-        assert!(!xml.contains('\n'), "applist must contain no newlines: {xml}");
+        assert!(
+            !xml.contains('\n'),
+            "applist must contain no newlines: {xml}"
+        );
         assert!(
             !xml.contains("> <"),
             "applist must contain no inter-element spaces: {xml}"