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-http/src/server/axum_server.rs

@@ -1,9 +1,6 @@
 //! Axum-based HTTP server with health endpoint.
 
-use axum::{
-    routing::get,
-    Router,
-};
+use axum::{routing::get, Router};
 use std::net::SocketAddr;
 
 /// A pre-configured HTTP server with health check and metrics endpoints.
@@ -19,10 +16,7 @@ impl HttpServer {
             .route("/health", get(|| async { "OK" }))
             .route("/", get(|| async { "mytheclipse-http" }));
 
-        Self {
-            app: router,
-            addr,
-        }
+        Self { app: router, addr }
     }
 
     /// Adds a custom route with a GET handler.