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- Remove outdated dependencies and update dependency versions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

remote/find_remote.rs

@@ -11,6 +11,7 @@ pub fn find_remote_repository(
             exists: false,
         });
     }
+    crate::sanitize::validate_remote_url(&request.remote_url)?;
 
     let output = std::process::Command::new("git")
         .args(["ls-remote", "--symref", &request.remote_url])
@@ -78,6 +79,11 @@ pub fn find_remote_repository(
 pub fn find_remote_root_ref(
     request: FindRemoteRootRefRequest,
 ) -> GitResult<FindRemoteRootRefResponse> {
+    if request.remote_url.is_empty() {
+        return Ok(FindRemoteRootRefResponse::default());
+    }
+    crate::sanitize::validate_remote_url(&request.remote_url)?;
+
     let output = std::process::Command::new("git")
         .args(["ls-remote", "--symref", &request.remote_url, "HEAD"])
         .stdout(std::process::Stdio::piped())
@@ -87,6 +93,9 @@ pub fn find_remote_root_ref(
             status_code: None,
             stderr: e.to_string(),
         })?;
+    if !output.status.success() {
+        return Ok(FindRemoteRootRefResponse::default());
+    }
 
     let stdout = String::from_utf8_lossy(&output.stdout);
     for line in stdout.lines() {