Code-attribution report can be computed against a different repo root than the current session

The code-attribution report, which totals up how much of your code came from Claude versus a human, could get confused about which repository it was reporting on. It now separately resolves the repo root that was actually requested and the repo root the current session is really using, and only re-fetches ignored-file information for each root when they differ. Each file's Human/Claude split is now looked up using a key that includes which root it belongs to, with a fallback if the root doesn't match.