fix(ci): restore full CI green — test-matrix, clippy, rustfmt, and rustdoc gates

Root cause of the failing CI run was that examples/tests referencing
feature-gated items were auto-detected (no required-features), so
`--all-targets` compiled them under feature combinations where those
modules didn't exist. Fixes:

- mytheclipse Cargo.toml: declare the `high_level` example and
  `race_stress` integration test with required-features = ["full"];
  `cargo build --all-targets` now skips them when full is off. This
  clears the whole test-matrix (workspace default, all-features, and
  every single-feature config) which all failed on E0432/E0433.
- lib.rs: auto_metrics_service depends on service_builder, so regate it
  behind all(observability, resiliency) instead of observability alone
  (observability-only build compiled the module without resiliency).
- mytheclipse-tracing: gate `pub mod fmt` behind any
  tracing-subscriber-providing feature so --no-default-features compiles.
- mytheclipse-queue: gate `pub mod worker` behind in-memory (worker.rs
  requires tokio, only provided by in-memory).
- clippy -D warnings fixes: deprecated base64 0.22 free fns -> Engine
  (paseto), unused key field, needless mut (service_builder), unused
  import/dead var/missing is_empty (bg_join), dead is_expired (dlock),
  while-let-iterator->for (parallel_map), type_complexity (shutdown_guard),
  MutexGuard held across await (middleware, now clones Arc'd layers),
  if-let-Err->is_err (queue), unused CliBuilder fields now wired into clap.
- rustdoc -D warnings: resolve retry/MetricsBridge/CircuitBreaker/KeyRing
  intra-doc links and fix the unparseable lifecycle.rs code fence.
- cargo fmt --all to satisfy the Rustfmt gate.

crates/mytheclipse-queue/tests/rate_limited_stress.rs

@@ -36,7 +36,11 @@ async fn rate_limited_queue_no_item_loss_under_contention() {
         let s = Arc::clone(&seen);
         workers.push(tokio::spawn(async move {
             loop {
-                match q.dequeue("stress", Duration::from_millis(50)).await.unwrap() {
+                match q
+                    .dequeue("stress", Duration::from_millis(50))
+                    .await
+                    .unwrap()
+                {
                     Some(job) => {
                         let _ = String::from_utf8(job.payload).unwrap();
                         s.fetch_add(1, Ordering::SeqCst);
@@ -64,4 +68,4 @@ async fn rate_limited_queue_no_item_loss_under_contention() {
         TASKS * PER_TASK,
         "items lost under contention"
     );
-}
+}