Enhance logging and fix regression in TODO.txt

- Updated the logging format in TODO.txt to provide clearer information about file operations and potential issues, including warnings about lossy string conversions.
- Added a note to address a regression in logging behavior that may affect users relying on specific property formats.
- Refactored the `flatten_tree` function in `git.rs` to improve parameter clarity by renaming the repository argument.
- Updated the `mcp.rs` test to utilize a more concise method for checking integer types in the timeout configuration.
- Introduced a new method in `TestServeSession` to fetch git metadata, improving the test suite's ability to validate git-related functionality.

These changes aim to improve logging clarity, address regressions, and enhance test coverage for git metadata handling.

src/git.rs

@@ -212,7 +212,7 @@ fn collect_tree_index_changes(
 }
 
 fn flatten_tree(
-    repo: &gix::Repository,
+    _repo: &gix::Repository,
     tree: &gix::Tree<'_>,
     prefix: &str,
     out: &mut HashMap<String, gix::ObjectId>,