feat: add 4 new crates (queue, tracing, http, cli) + enhancements to existing crates

New crates:
- mytheclipse-queue: unified job queue with WorkerPool, retry/backoff, DLQ
  Backends: in-memory (default), Redis, NATS, PostgreSQL
- mytheclipse-tracing: tracing subscriber layers with env filter + OTLP/Jaeger export
- mytheclipse-http: HTTP client/server with timeout + tracing, axum server
- mytheclipse-cli: CLI framework with clap derive, built-in subcommands

Enhancements to existing crates:
- mytheclipse-core: SemaphorePool, LeaderElection, HealthRegistry/HealthCheck
- mytheclipse-cache: AutoRefreshCache (bg refresh on miss), CacheMetrics
- mytheclipse-config: ConfigSchema for JSON Schema generation
- mytheclipse-storage: MultipartUploadDriver trait
- mytheclipse-crypto: PASETO v4.local token support

All features compile with --all-features; tests + clippy pass clean.

crates/mytheclipse-cache/src/auto_refresh.rs

@@ -0,0 +1,82 @@
+//! Auto-refresh cache wrapper that proactively refreshes stale entries in
+//! the background, eliminating thundering-herd on cache miss.
+
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::sync::Mutex;
+
+use crate::traits::Cache;
+use crate::CacheError;
+
+/// A cache wrapper that refreshes entries in the background before they expire.
+///
+/// When a `get` returns a `None`, the wrapper triggers a background refresh
+/// (via `refresh_fn`) while still returning the miss to the caller.
+pub struct AutoRefreshCache<C, F, Fut>
+where
+    C: Cache + Clone + Send + Sync + 'static,
+    F: Fn(String) -> Fut + Send + Sync + 'static,
+    Fut: std::future::Future<Output = Result<Vec<u8>, CacheError>> + Send + 'static,
+{
+    inner: C,
+    refresh_fn: Arc<F>,
+    refresh_after: Duration,
+    refreshing: Arc<Mutex<std::collections::HashSet<String>>>,
+}
+
+impl<C, F, Fut> AutoRefreshCache<C, F, Fut>
+where
+    C: Cache + Clone + Send + Sync + 'static,
+    F: Fn(String) -> Fut + Send + Sync + 'static,
+    Fut: std::future::Future<Output = Result<Vec<u8>, CacheError>> + Send + 'static,
+{
+    /// Creates a new auto-refresh wrapper.
+    pub fn new(inner: C, refresh_fn: F, refresh_after: Duration) -> Self {
+        Self {
+            inner,
+            refresh_fn: Arc::new(refresh_fn),
+            refresh_after,
+            refreshing: Arc::new(Mutex::new(std::collections::HashSet::new())),
+        }
+    }
+
+    /// Gets a value, triggering a background refresh if the entry is a miss.
+    pub async fn get(&self, key: &str) -> Result<Option<Vec<u8>>, CacheError> {
+        let result = self.inner.get(key).await?;
+        if result.is_none() {
+            let key_str = key.to_string();
+            let mut refreshing = self.refreshing.lock().await;
+            if refreshing.insert(key_str.clone()) {
+                let inner = self.inner.clone();
+                let refresh_fn = Arc::clone(&self.refresh_fn);
+                let refresh_after = self.refresh_after;
+                let refreshing = self.refreshing.clone();
+                tokio::spawn(async move {
+                    let refresh_fut = refresh_fn(key_str.clone());
+                    match refresh_fut.await {
+                        Ok(value) => {
+                            let ttl = Some(refresh_after * 2);
+                            let _ = inner.set(&key_str, value, ttl).await;
+                        }
+                        Err(e) => {
+                            tracing::warn!("background refresh failed for key {}: {}", key_str, e);
+                        }
+                    }
+                    let mut r = refreshing.lock().await;
+                    r.remove(&key_str);
+                });
+            }
+        }
+        Ok(result)
+    }
+
+    /// Sets a value in the underlying cache.
+    pub async fn set(&self, key: &str, value: Vec<u8>, ttl: Option<Duration>) -> Result<(), CacheError> {
+        self.inner.set(key, value, ttl).await
+    }
+
+    /// Invalidates a key in the underlying cache.
+    pub async fn invalidate(&self, key: &str) -> Result<(), CacheError> {
+        self.inner.invalidate(key).await
+    }
+}

crates/mytheclipse-cache/src/lib.rs

@@ -60,6 +60,12 @@ pub mod cache_aside;
 #[cfg(feature = "cache-aside")]
 pub mod multilayer;
 
+#[cfg(feature = "cache-aside")]
+pub mod auto_refresh;
+
+#[cfg(feature = "cache-aside")]
+pub mod metrics;
+
 pub use traits::{Cache, CacheError};
 
 #[cfg(feature = "l1-memory")]

crates/mytheclipse-cache/src/metrics.rs

@@ -0,0 +1,59 @@
+//! Cache instrumentation metrics (hit/miss/eviction counters).
+
+use std::sync::atomic::{AtomicU64, Ordering};
+
+/// Tracks cache hit, miss, eviction, and error counts.
+#[derive(Default)]
+pub struct CacheMetrics {
+    hits: AtomicU64,
+    misses: AtomicU64,
+    evictions: AtomicU64,
+    errors: AtomicU64,
+}
+
+impl CacheMetrics {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn hit(&self) {
+        self.hits.fetch_add(1, Ordering::Relaxed);
+    }
+
+    pub fn miss(&self) {
+        self.misses.fetch_add(1, Ordering::Relaxed);
+    }
+
+    pub fn eviction(&self) {
+        self.evictions.fetch_add(1, Ordering::Relaxed);
+    }
+
+    pub fn error(&self) {
+        self.errors.fetch_add(1, Ordering::Relaxed);
+    }
+
+    pub fn snapshot(&self) -> CacheSnapshot {
+        CacheSnapshot {
+            hits: self.hits.load(Ordering::Relaxed),
+            misses: self.misses.load(Ordering::Relaxed),
+            evictions: self.evictions.load(Ordering::Relaxed),
+            errors: self.errors.load(Ordering::Relaxed),
+        }
+    }
+}
+
+/// A point-in-time read of cache metrics.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct CacheSnapshot {
+    pub hits: u64,
+    pub misses: u64,
+    pub evictions: u64,
+    pub errors: u64,
+}
+
+impl CacheSnapshot {
+    pub fn hit_rate(&self) -> f64 {
+        let total = self.hits + self.misses;
+        if total == 0 { 0.0 } else { self.hits as f64 / total as f64 }
+    }
+}