style(enroll): cargo fmt --all (satisfy CI fmt gate)

The Phase A work passed cargo check + clippy + tests locally but missed
`cargo fmt --all -- --check` (the first step of the Linux CI job): module
ordering in db/mod.rs and two trailing-comment alignments in rate_limit.rs.
No logic change. Agent build failure on the prior run was transient infra
(verified: agent crate compiles clean locally).

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

server/src/middleware/rate_limit.rs

@@ -708,7 +708,7 @@ mod tests {
         let t0 = Instant::now();
         assert!(lim.check_at("SITE-A", ip(1), t0));
         assert!(!lim.check_at("SITE-A", ip(1), t0)); // same key over cap
-        // Different site, same IP -> independent bucket.
+                                                     // Different site, same IP -> independent bucket.
         assert!(lim.check_at("SITE-B", ip(1), t0));
         // Same site, different IP -> independent bucket.
         assert!(lim.check_at("SITE-A", ip(2), t0));
@@ -723,7 +723,7 @@ mod tests {
         // Not yet tripped: a check still admits.
         assert!(lim.check_at("SITE-A", ip(1), t0));
         lim.record_failure_at("SITE-A", ip(1), t0); // 3rd -> trips
-        // Now locked out: check denies even though under the request cap.
+                                                    // Now locked out: check denies even though under the request cap.
         assert!(!lim.check_at("SITE-A", ip(1), t0));
     }