chore(release): 0.2.0

[Muawiya-contact]

What & why

Cuts 0.2.0. 191 commits since v0.1.1, +6219/−2160 across 57 files.

Two commits:

• Version bump. v0.1.1 was tagged back in July without moving the
  version off 0.1.0, so Cargo.toml, app/src-tauri/tauri.conf.json,
  app/package.json and the tag have disagreed ever since. All four now
  say 0.2.0.
• Changelog. Dates the section that had been accumulating under
  Unreleased, and leaves an empty Unreleased heading for the next
  change. Three entries were corrected against the commits they describe:
  --rules now records the pattern validation and protected-rule
  ordering that shipped with it, and two fixes (empty-quarantine purge,
  two-marker project directories) had landed without being written down.

Minor, not patch: the release adds CLI flags, a Quarantine panel, scan
cancellation and the impact graph, and changes rule matching from
substrings to anchored globs.

Headline changes

• Rule patterns are anchored globs, not substrings — /tmp no longer
  matches ~/tmp, and the Firefox rule covers cache2 rather than the
  whole profile
• The impact graph reaches the report: a dependency store a live project
  depends on is marked more cautiously than an abandoned one
• Quarantine keeps a manifest, so a file can be restored after the app
  is closed; the app gained a Quarantine panel with restore and purge
• diskern scan prints the findings, with --top, --verdict and
  --rules
• Scans can be cancelled from the app
• The reclaimable headline stopped counting the same bytes twice, and
  stopped counting bytes on files nothing will act on

Validation

• cargo fmt --all -- --check
• cargo clippy -p diskern-core -p diskern-cli --all-targets -- -D warnings
• cargo test -p diskern-core -p diskern-cli — 66 pass, 0 fail

After merge

git tag v0.2.0 && git push --tags builds the artifacts into a draft
release for review before publishing, per docs/RELEASING.md.