Dix 2.0: More info, more diff, more good!

Added

• Added the dix-diff crate for the pure package/version diff engine. This
  crate contains the core diff model and algorithms, but does not depend on any
  Nix-specific data sources or APIs. It is intended for users who want to
  perform package/version diffs without needing to query the Nix store, and for
  users who want to build on top of the diff engine with their own custom data
  sources or APIs.
• Added public diff event types for version-level changes: VersionDiff,
  VersionAmount, and the AmountChanged event for count-only changes.
• Added PackageSnapshot and diff_snapshots for callers that want to diff
  package/version data without querying the Nix store.
• Added root dix re-exports for the main diff model types: DiffStatus,
  Version, VersionAmount, and VersionDiff.
• Added exact closure path statistics to reports. Human output now shows old
  and new closure path counts plus exact added and removed store path counts,
  and JSON output includes the same data in the paths object.
• Added package size deltas to reports. Human output shows significant
  per-package NAR size changes, and JSON diff entries include old, new, and
  delta size fields in bytes.

Changed

• Changed the repository layout from a single Cargo package to a workspace.
  Source installs now use cargo install --path crates/dix.
• Changed the Rust diff model from separate old and new version lists to a
  versions event list.
• Changed diff statuses from DiffStatus::Changed(Change::...) to flat variants
  such as Changed, Mixed, Upgraded, and Downgraded.
• Changed version counts to use VersionAmount and VersionDiff::AmountChanged
  instead of storing counts on Version.
• Changed version parsing and status classification to treat Git short or full
  hash suffixes as unordered versions. These changes are now reported as
  changed instead of arbitrary upgrades or downgrades.
• Changed report querying from DiffReport::query(...) to the
  query_diff_report(...) free function.
• Changed DiffReport and PathStats to expose read-only accessor methods
  instead of public fields.
• Changed JSON output. Diff entries now contain tagged versions events and
  has_omitted_versions instead of old, new, and has_common_versions,
  and reports include exact closure path statistics in paths.

Removed

• Removed the old dix::diff and dix::version module paths.
• Removed generate_diffs_from_paths(...) and match_version_lists(...) from
  the dix public API.
• Removed the public DiffReport::between(...) constructor. Store-backed
  reports should be built with query_diff_report(...); pure package/version
  diffs should use dix-diff.
• Removed the Change enum.
• Removed Version.amount.
• Removed direct serde serialization of the public diff model types.

Breaking Changes

• cargo install --path . no longer works because the repository root is now a
  workspace manifest. Use cargo install --path crates/dix instead.
• Rust users importing dix::diff or dix::version must update their imports.
  The main diff model types are re-exported from dix; lower-level engine APIs
  live in dix-diff.
• Rust users constructing or matching diffs must migrate from the old
  old/new list model to the new VersionDiff event model.
• Rust users matching DiffStatus::Changed(Change::...) must migrate to the new
  flat DiffStatus variants.
• Rust users reading or writing Version.amount must use VersionAmount or
  VersionDiff::AmountChanged instead.
• Rust users calling DiffReport::query(...) must call query_diff_report(...)
  instead.
• Rust users calling DiffReport::between(...) must use
  query_diff_report(...) for store-backed reports or dix-diff for pure
  package/version diffs.
• Rust users reading DiffReport or PathStats fields directly must use the
  new accessor methods instead. Direct construction of DiffReport is no
  longer supported.
• Rust users implementing dix::store::StoreBackend must implement
  query_closure_path_info(...). The default query_closure_size(...)
  implementation now derives aggregate closure size from that path info.
• JSON consumers must update to the new --output json schema. The old old,
  new, and has_common_versions fields are no longer emitted, and exact
  closure path statistics are emitted in the new paths object. Diff entries
  also include size_old, size_new, and size_delta fields.

What's Changed

• docs: update dix pic by @faukah in #52
• big cleanup, tests by @faukah in #53
• Json output by @Dragyx in #51
• nix.yml: update action versions by @faukah in #54
• store: clean up StoreBackend by @faukah in #62
• split up dix into dix-diff and dix by @faukah in #64
• change size diff colors by @SandaruKasa in #65
• dix: show exact path stat difference by @faukah in #66
• dix: mark git shorthashes as changes instead of up/downgrades by @faukah in #67
• dix: add package size deltas to reports by @faukah in #70
• dix: canonicalize old path as well by @faukah in #71
• dix: strip .drv suffixes by @faukah in #72
• dix: rename to by @faukah in #73

New Contributors

• @SandaruKasa made their first contribution in #65

Full Changelog: v1.4.2...v2.0.0