refactor(actor): implement Raft consensus algorithm for cluster leader election

- Add voting mechanism with term tracking and vote persistence
- Implement election triggering logic with majority vote counting
- Add primary/replica role transition handling with state management
- Integrate health check failure detection for automatic elections
- Refactor actor messaging system for distributed coordination
- Update repository registration to query cluster for existing primary
- Add broadcast mechanism for role change notifications
- Implement proper term comparison and duplicate request filtering
- Upgrade dependency versions including tokio-util for async utilities
- Optimize code formatting and line wrapping for improved readability
- Remove redundant blank lines and improve code structure consistency
- Enhance error logging and trace information for debugging purposes

disk_cache.rs

@@ -94,7 +94,6 @@ impl DiskCache {
         self.enabled
     }
 
-
     fn state_dir_for(&self, relative_path: &str) -> PathBuf {
         self.repo_prefix
             .join(STATE_DIR_RELATIVE)
@@ -109,7 +108,6 @@ impl DiskCache {
         self.state_dir_for(relative_path).join("pending")
     }
 
-
     fn cache_dir(&self, namespace: &str) -> PathBuf {
         self.repo_prefix.join(namespace)
     }
@@ -118,7 +116,6 @@ impl DiskCache {
         self.cache_dir(namespace).join(digest_to_path(digest))
     }
 
-
     /// Ensure the state directory for a repository exists and has a `latest` file.
     /// If `latest` does not exist, create it with a random value.
     pub fn ensure_state(&self, relative_path: &str) -> GitResult<String> {
@@ -230,7 +227,6 @@ impl DiskCache {
         Ok(())
     }
 
-
     /// Compute a cache key for an info/refs request.
     pub fn compute_info_refs_key(&self, relative_path: &str, protocol: &str) -> GitResult<String> {
         let latest = self.ensure_state(relative_path)?;
@@ -268,7 +264,6 @@ impl DiskCache {
         Ok(sha256_digest(parts))
     }
 
-
     /// Look up a cached response for the given namespace and digest.
     /// Returns the cached bytes if found and not expired.
     pub fn lookup(&self, namespace: &str, digest: &str) -> GitResult<Option<Vec<u8>>> {