Three pure functions — overview / repo_summary / pr_summary — that open
the feedback SQLite via feedback.init, run their queries, and return
plain dicts/lists. All three tolerate a missing or empty DB by returning
a zero-shaped dict.
Cost is hardcoded 0.0: per-review usage:cost isn't stored, only the raw
review rows are. Surfacing a rolled-up dollar figure without telemetry
would be guessing, so we don't.
17 new tests under tests/pilot/test_dashboard_data.py.
Claude