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- Remove outdated dependencies and update dependency versions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

branch/update_branch_target.rs

@@ -14,11 +14,13 @@ impl GitBare {
             .ok_or_else(|| GitError::InvalidArgument("new_oid is required".into()))?
             .hex
             .clone();
+        crate::sanitize::validate_oid_hex(&new_oid)?;
         let refname = format!("refs/heads/{}", request.name);
         let mut args = vec!["update-ref".to_string(), refname.clone(), new_oid];
         if !request.force
             && let Some(old) = request.expected_old_oid.as_ref()
         {
+            crate::sanitize::validate_oid_hex(&old.hex)?;
             args.push(old.hex.clone());
         }
         let output = Command::new("git")