v0.6.1

Fixed

• Done-claim validation received empty or misleading diff evidence. stop-done-claim.sh summarized the work with git diff --stat HEAD~1, which produced nothing usable in four common cases: an unborn HEAD (the first commit not yet made), a root commit (no parent, so HEAD~1 errors out), a multi-commit task (only the most recent commit was shown, hiding the rest of the work), and uncommitted changes (HEAD~1 ignores the working tree entirely). In each case the gemini-validator was handed weak evidence to audit the "done" claim against. Fixed by adding build_diff_summary() to hooks/lib/common.sh: it shows staged work on an unborn HEAD, uncommitted changes against HEAD, and the whole branch since it forked from the default branch (detected as origin/main, main, or master), falling back to HEAD~1 and then the single commit when no fork point exists.