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- Remove outdated dependencies and update dependency versions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

diff/changed_paths.rs

@@ -19,16 +19,17 @@ impl GitBare {
             "-r".to_string(),
         ];
 
-        if !request.paths.is_empty() {
-            args.push("--".to_string());
-            for p in &request.paths {
-                args.push(p.clone());
-            }
-        }
-
         args.push(request.base.clone());
         args.push(request.head.clone());
 
+        if !request.paths.is_empty() {
+            args.push("--".to_string());
+            for path in &request.paths {
+                crate::sanitize::validate_file_path(path)?;
+                args.push(path.clone());
+            }
+        }
+
         let output = std::process::Command::new("git")
             .args(&args)
             .stdout(std::process::Stdio::piped())
@@ -38,6 +39,12 @@ impl GitBare {
                 status_code: None,
                 stderr: e.to_string(),
             })?;
+        if !output.status.success() {
+            return Err(crate::error::GitError::CommandFailed {
+                status_code: output.status.code(),
+                stderr: String::from_utf8_lossy(&output.stderr).trim().to_string(),
+            });
+        }
 
         let stdout = String::from_utf8_lossy(&output.stdout);
         let mut paths = Vec::new();