feat(api): extend commit and diff services with new functionality

- Add FindCommit, ListCommitsByOid, CommitIsAncestor RPCs to CommitService
- Add CheckObjectsExist, CommitsByMessage, GetCommitStats RPCs to CommitService
- Add LastCommitForPath, CountCommits, CountDivergingCommits RPCs to CommitService
- Add RawDiff, RawPatch, FindChangedPaths RPCs to DiffService
- Add FindMergeBase, WriteRef, SearchFilesByContent RPCs to RepositoryService
- Add SearchFilesByName, ObjectsSize, RepositorySize RPCs to RepositoryService
- Add FindLicense, OptimizeRepository, GetRawChanges RPCs to RepositoryService
- Add FetchRemote, CreateRepositoryFromURL RPCs to RepositoryService
- Implement server handlers for all new RPC methods
- Add new modules for commit counting, finding, and querying features
- Add new modules for diff changed paths and raw operations
- Add new modules for refs and remote operations
- Remove unnecessary comments from various source files
- Update proto definitions with new message types and service methods

diff/changed_paths.rs

@@ -0,0 +1,73 @@
+use crate::bare::GitBare;
+use crate::error::GitResult;
+use crate::pb::*;
+
+impl GitBare {
+    /// Find changed paths between two revisions (no diff content).
+    pub fn find_changed_paths(&self, request: FindChangedPathsRequest) -> GitResult<FindChangedPathsResponse> {
+        crate::sanitize::validate_revision(&request.base)?;
+        crate::sanitize::validate_revision(&request.head)?;
+
+        let mut args = vec![
+            "--git-dir".to_string(),
+            self.bare_dir.to_string_lossy().into_owned(),
+            "diff-tree".to_string(),
+            "--name-status".to_string(),
+            "-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());
+
+        let output = std::process::Command::new("git")
+            .args(&args)
+            .stdout(std::process::Stdio::piped())
+            .stderr(std::process::Stdio::piped())
+            .output()
+            .map_err(|e| crate::error::GitError::CommandFailed {
+                status_code: None,
+                stderr: e.to_string(),
+            })?;
+
+        let stdout = String::from_utf8_lossy(&output.stdout);
+        let mut paths = Vec::new();
+
+        for line in stdout.lines() {
+            let line = line.trim();
+            if line.is_empty() { continue; }
+
+            let parts: Vec<&str> = line.split('\t').collect();
+            if parts.is_empty() { continue; }
+
+            let status_str = parts[0];
+            let status_letter = status_str.chars().next().unwrap_or('M');
+
+            let (status, old_path, new_path) = match status_letter {
+                'A' => (changed_path::Status::ChangedPathStatusAdded as i32, String::new(), parts.get(1).cloned().unwrap_or_default().to_string()),
+                'D' => (changed_path::Status::ChangedPathStatusDeleted as i32, parts.get(1).cloned().unwrap_or_default().to_string(), String::new()),
+                'R' => (changed_path::Status::ChangedPathStatusRenamed as i32, parts.get(1).cloned().unwrap_or_default().to_string(), parts.get(2).cloned().unwrap_or_default().to_string()),
+                'C' => (changed_path::Status::ChangedPathStatusCopied as i32, parts.get(1).cloned().unwrap_or_default().to_string(), parts.get(2).cloned().unwrap_or_default().to_string()),
+                'T' => (changed_path::Status::ChangedPathStatusTypeChanged as i32, String::new(), parts.get(1).cloned().unwrap_or_default().to_string()),
+                _ => (changed_path::Status::ChangedPathStatusModified as i32, String::new(), parts.get(1).cloned().unwrap_or_default().to_string()),
+            };
+
+            paths.push(ChangedPath {
+                status,
+                old_path,
+                new_path,
+                additions: 0,
+                deletions: 0,
+                binary: false,
+            });
+        }
+
+        Ok(FindChangedPathsResponse { paths })
+    }
+}