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- Remove outdated dependencies and update dependency versions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

commit/find_commit.rs

@@ -6,7 +6,10 @@ impl GitBare {
     /// Find a single commit by revision.
     pub fn find_commit(&self, request: FindCommitRequest) -> GitResult<Commit> {
         let revision = match request.revision.and_then(|s| s.selector) {
-            Some(object_selector::Selector::Oid(oid)) => oid.hex,
+            Some(object_selector::Selector::Oid(oid)) => {
+                crate::sanitize::validate_oid_hex(&oid.hex)?;
+                oid.hex
+            }
             Some(object_selector::Selector::Revision(name)) => name.revision,
             None => "HEAD".to_string(),
         };