Stamped at build time via QUIRE_VERSION (build.rs already exposes this
to main); the index page becomes a quick "what build is serving here"
check.

Assisted-by: Claude Opus 4.7 via Claude Code

diff --git a/src/bin/quire/server.rs b/src/bin/quire/server.rs
index 17dffab..9db3aa9 100644
--- a/src/bin/quire/server.rs
+++ b/src/bin/quire/server.rs
@@ -13,8 +13,8 @@ async fn health() -> &'static str {
     "ok"
 }
 
-async fn index() -> &'static str {
-    "quire\n"
+async fn index() -> String {
+    format!("quire {}\n", crate::VERSION)
 }
 
 pub async fn run(quire: &Quire) -> Result<()> {