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

rate_limit.rs

@@ -12,7 +12,6 @@ use dashmap::DashMap;
 use std::sync::{Arc, OnceLock};
 use tokio::sync::Semaphore;
 
-// ── Configuration ───────────────────────────────────────────────────
 
 /// Default max concurrent operations per repository.
 const DEFAULT_MAX_CONCURRENT: usize = 5;
@@ -46,7 +45,6 @@ fn limiter() -> &'static RateLimiter {
     })
 }
 
-// ── Permit guard ───────────────────────────────────────────────────
 
 /// A guard that holds a rate-limit permit. The permit is released on drop.
 pub struct RateLimitGuard {