Adds FileStatEntry type and two new primitives to the BranchManager
port and SimpleGitBranchManager adapter, enabling split diff
procedures in the tRPC layer without returning raw multi-megabyte diffs.
- FileStatEntry captures path, status, additions/deletions, oldPath
(renames), and optional projectId for multi-project routing
- diffBranchesStat uses --name-status + --numstat, detects binary
files (shown as - / - in numstat), handles spaces in filenames
- diffFileSingle returns raw unified diff for a single file path
05eb160749