refactor(cache): redesign cache system with structured keys and improved performance

- Add repo_path parameter to cached_response and cached_vec_response functions
- Implement structured cache key format with namespace, repo_path, and request proto
- Replace global cache with Moka in-memory cache using weight-based eviction
- Set 256MB memory cap with 10-minute TTL and 2-minute TTI policy
- Add metrics collection for cache operations and evictions
- Implement efficient repo-scoped invalidation using key structure
- Add detailed documentation comments explaining cache architecture
- Remove outdated dependencies and update dependency versions
- Add error handling for encoding failures in cache operations
- Optimize Vec responses with length-delimited encoding and pre-allocation

tests/oid_test.rs

@@ -31,6 +31,12 @@ fn test_hex_to_bytes_invalid_hex() {
     assert!(result.is_err());
 }
 
+#[test]
+fn test_hex_to_bytes_non_ascii_does_not_panic() {
+    let result = hex_to_bytes("aéx");
+    assert!(result.is_err());
+}
+
 #[test]
 fn test_hex_to_bytes_with_whitespace() {
     let bytes = hex_to_bytes("  abcd  ").unwrap();