Release v1.5.0

Summary

Make the human-time estimate auditable without turning reports into an attendance claim. The calculation now has one versioned source of truth, an opt-in structural ledger for people and API consumers, and explicit safeguards around block overlap, precision, and sensitive metadata.

Release notes are generated from this description:

Added

• Add --explain-human-time for a readable table ledger and structured JSON details covering scoped/effective signals, timestamp deduplication, block boundaries, credit, clipping, and the reconciled total.
• Add stable signal-blocks-v1 algorithm, timezone, and boundary-basis metadata to JSON reports.
• Add privacy and reconciliation regression coverage, including exact half-millisecond ties and equal-priority timestamp collisions.

Changed

• Calculate human-time intervals, block explanations, and the summary total through one shared path.
• Round the final total from exact integer microseconds with ties-to-even, exposing the unrounded block subtotal and rounding adjustment for auditability.
• Reject --explain-human-time for CSV and the TUI, whose output shapes cannot represent the one-to-many ledger without ambiguity.

Fixed

• Reject --review-credit values greater than --human-idle, preventing separately clustered work blocks from overlapping and counting time twice.

Privacy

• Explanation output includes structural timestamps, signal kinds, providers, and repository labels only; it excludes prompt/response text, raw session IDs, cwd/root paths, model names, and commit hashes.

Verification

• cargo test — 232 unit tests and 10 integration tests passed.
• cargo clippy --all-targets -- -D warnings — passed.
• cargo fmt --check — passed.
• git diff --check — passed.
• Two structured validation reviews completed; all findings were addressed before opening this PR.