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- Remove outdated dependencies and update dependency versions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

blob/get_blob.rs

@@ -10,6 +10,7 @@ impl GitBare {
         let repo = self.gix_repo()?;
         let revision = tree::resolve_revision(&request.revision)?;
         let (blob, mode, path) = if let Some(oid) = request.oid.as_ref() {
+            crate::sanitize::validate_oid_hex(&oid.hex)?;
             let id = gix::hash::ObjectId::from_hex(oid.hex.as_bytes())
                 .map_err(|e| GitError::InvalidOid(e.to_string()))?;
             (
@@ -20,6 +21,7 @@ impl GitBare {
                 request.path,
             )
         } else {
+            crate::sanitize::validate_file_path(&request.path)?;
             let tree = repo
                 .rev_parse_single(format!("{}^{{tree}}", revision).as_str())?
                 .object()?